Difference between revisions of "2012 AMC 10A Problems"
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+ | {{AMC10 Problems|year=2012|ab=A}} | ||
== Problem 1 == | == Problem 1 == | ||
− | Cagney can frost a cupcake every 20 seconds and Lacey can frost a cupcake every 30 seconds. Working together, how many cupcakes can they frost in 5 minutes? | + | Cagney can frost a cupcake every <math>20</math> seconds and Lacey can frost a cupcake every <math>30</math> seconds. Working together, how many cupcakes can they frost in <math>5</math> minutes? |
<math> \textbf{(A)}\ 10\qquad\textbf{(B)}\ 15\qquad\textbf{(C)}\ 20\qquad\textbf{(D)}\ 25\qquad\textbf{(E)}\ 30 </math> | <math> \textbf{(A)}\ 10\qquad\textbf{(B)}\ 15\qquad\textbf{(C)}\ 20\qquad\textbf{(D)}\ 25\qquad\textbf{(E)}\ 30 </math> | ||
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== Problem 2 == | == Problem 2 == | ||
− | A square with side length 8 is cut in half, creating two congruent rectangles. What are the dimensions of one of these rectangles? | + | A square with side length <math>8</math> is cut in half, creating two congruent rectangles. What are the dimensions of one of these rectangles? |
<math> \textbf{(A)}\ 2\ \text{by}\ 4\qquad\textbf{(B)}\ \ 2\ \text{by}\ 6\qquad\textbf{(C)}\ \ 2\ \text{by}\ 8\qquad\textbf{(D)}\ 4\ \text{by}\ 4\qquad\textbf{(E)}\ 4\ \text{by}\ 8 </math> | <math> \textbf{(A)}\ 2\ \text{by}\ 4\qquad\textbf{(B)}\ \ 2\ \text{by}\ 6\qquad\textbf{(C)}\ \ 2\ \text{by}\ 8\qquad\textbf{(D)}\ 4\ \text{by}\ 4\qquad\textbf{(E)}\ 4\ \text{by}\ 8 </math> | ||
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== Problem 3 == | == Problem 3 == | ||
− | A bug crawls along a number line, starting at -2. It crawls to -6, then turns around and crawls to 5. How many units does the bug crawl altogether? | + | A bug crawls along a number line, starting at <math>-2</math>. It crawls to <math>-6</math>, then turns around and crawls to <math>5</math>. How many units does the bug crawl altogether? |
<math> \textbf{(A)}\ 9\qquad\textbf{(B)}\ 11\qquad\textbf{(C)}\ 13\qquad\textbf{(D)}\ 14\qquad\textbf{(E)}\ 15 </math> | <math> \textbf{(A)}\ 9\qquad\textbf{(B)}\ 11\qquad\textbf{(C)}\ 13\qquad\textbf{(D)}\ 14\qquad\textbf{(E)}\ 15 </math> | ||
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== Problem 4 == | == Problem 4 == | ||
− | Let <math>\angle ABC = 24^\circ </math> and <math>\angle ABD = 20^\circ </math>. What is the smallest possible degree measure for angle CBD? | + | Let <math>\angle ABC = 24^\circ </math> and <math>\angle ABD = 20^\circ </math>. What is the smallest possible degree measure for angle <math>CBD</math>? |
<math> \textbf{(A)}\ 0\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 4\qquad\textbf{(D)}\ 6\qquad\textbf{(E)}\ 12 </math> | <math> \textbf{(A)}\ 0\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 4\qquad\textbf{(D)}\ 6\qquad\textbf{(E)}\ 12 </math> | ||
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== Problem 5 == | == Problem 5 == | ||
− | Last year 100 adult cats, half of whom were female, were brought into the Smallville Animal Shelter. Half of the adult female cats were accompanied by a litter of kittens. The average number of kittens per litter was 4. What was the total number of cats and kittens received by the shelter last year? | + | Last year <math>100</math> adult cats, half of whom were female, were brought into the Smallville Animal Shelter. Half of the adult female cats were accompanied by a litter of kittens. The average number of kittens per litter was <math>4</math>. What was the total number of cats and kittens received by the shelter last year? |
<math> \textbf{(A)}\ 150\qquad\textbf{(B)}\ 200\qquad\textbf{(C)}\ 250\qquad\textbf{(D)}\ 300\qquad\textbf{(E)}\ 400 </math> | <math> \textbf{(A)}\ 150\qquad\textbf{(B)}\ 200\qquad\textbf{(C)}\ 250\qquad\textbf{(D)}\ 300\qquad\textbf{(E)}\ 400 </math> | ||
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== Problem 6 == | == Problem 6 == | ||
− | The product of two positive numbers is 9. The reciprocal of one of these numbers is 4 times the reciprocal of the other number. What is the sum of the two numbers? | + | The product of two positive numbers is <math>9</math>. The reciprocal of one of these numbers is <math>4</math> times the reciprocal of the other number. What is the sum of the two numbers? |
<math> \textbf{(A)}\ \frac{10}{3}\qquad\textbf{(B)}\ \frac{20}{3}\qquad\textbf{(C)}\ 7\qquad\textbf{(D)}\ \frac{15}{2}\qquad\textbf{(E)}\ 8 </math> | <math> \textbf{(A)}\ \frac{10}{3}\qquad\textbf{(B)}\ \frac{20}{3}\qquad\textbf{(C)}\ 7\qquad\textbf{(D)}\ \frac{15}{2}\qquad\textbf{(E)}\ 8 </math> | ||
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== Problem 8 == | == Problem 8 == | ||
− | The sums of three whole numbers taken in pairs are 12, 17, and 19. What is the middle number? | + | The sums of three whole numbers taken in pairs are <math>12</math>, <math>17</math>, and <math>19</math>. What is the middle number? |
<math> \textbf{(A)}\ 4\qquad\textbf{(B)}\ 5\qquad\textbf{(C)}\ 6\qquad\textbf{(D)}\ 7\qquad\textbf{(E)}\ 8 </math> | <math> \textbf{(A)}\ 4\qquad\textbf{(B)}\ 5\qquad\textbf{(C)}\ 6\qquad\textbf{(D)}\ 7\qquad\textbf{(E)}\ 8 </math> | ||
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== Problem 9 == | == Problem 9 == | ||
− | A pair of six-sided dice are labeled so that one die has only even numbers (two each of 2, 4, and 6), and the other die has only odd numbers (two of | + | A pair of six-sided dice are labeled so that one die has only even numbers (two each of <math>2</math>, <math>4</math>, and <math>6</math>), and the other die has only odd numbers (two each of <math>1</math>, <math>3</math>, and <math>5</math>). The pair of dice is rolled. What is the probability that the sum of the numbers on the tops of the two dice is <math>7</math>? |
<math> \textbf{(A)}\ \frac{1}{6}\qquad\textbf{(B)}\ \frac{1}{5}\qquad\textbf{(C)}\ \frac{1}{4}\qquad\textbf{(D)}\ \frac{1}{3}\qquad\textbf{(E)}\ \frac{1}{2} </math> | <math> \textbf{(A)}\ \frac{1}{6}\qquad\textbf{(B)}\ \frac{1}{5}\qquad\textbf{(C)}\ \frac{1}{4}\qquad\textbf{(D)}\ \frac{1}{3}\qquad\textbf{(E)}\ \frac{1}{2} </math> | ||
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== Problem 10 == | == Problem 10 == | ||
− | Mary divides a circle into 12 sectors. The central angles of these sectors, measured in degrees, are all integers and they form an arithmetic sequence. What is the degree measure of the smallest possible sector angle? | + | Mary divides a circle into <math>12</math> sectors. The central angles of these sectors, measured in degrees, are all integers and they form an arithmetic sequence. What is the degree measure of the smallest possible sector angle? |
<math> \textbf{(A)}\ 5\qquad\textbf{(B)}\ 6\qquad\textbf{(C)}\ 8\qquad\textbf{(D)}\ 10\qquad\textbf{(E)}\ 12 </math> | <math> \textbf{(A)}\ 5\qquad\textbf{(B)}\ 6\qquad\textbf{(C)}\ 8\qquad\textbf{(D)}\ 10\qquad\textbf{(E)}\ 12 </math> | ||
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== Problem 11 == | == Problem 11 == | ||
− | Externally tangent circles with centers at points A and B have radii of lengths 5 and 3, respectively. A line externally tangent to both circles intersects ray AB at point C. What is BC? | + | Externally tangent circles with centers at points <math>A</math> and <math>B</math> have radii of lengths <math>5</math> and <math>3</math>, respectively. A line externally tangent to both circles intersects ray <math>AB</math> at point <math>C</math>. What is <math>BC</math>? |
<math> \textbf{(A)}\ 4\qquad\textbf{(B)}\ 4.8\qquad\textbf{(C)}\ 10.2\qquad\textbf{(D)}\ 12\qquad\textbf{(E)}\ 14.4 </math> | <math> \textbf{(A)}\ 4\qquad\textbf{(B)}\ 4.8\qquad\textbf{(C)}\ 10.2\qquad\textbf{(D)}\ 12\qquad\textbf{(E)}\ 14.4 </math> | ||
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== Problem 12 == | == Problem 12 == | ||
− | A year is a leap year if and only if the year number is divisible by 400 (such as 2000) or is divisible by 4 but not 100 (such as 2012). The | + | A year is a leap year if and only if the year number is divisible by <math>400</math> (such as <math>2000</math>) or is divisible by <math>4</math> but not <math>100</math> (such as <math>2012</math>). The <math>200</math>th anniversary of the birth of novelist Charles Dickens was celebrated on February <math>7</math>, <math>2012</math>, a Tuesday. On what day of the week was Dickens born? |
<math> \textbf{(A)}\ \text{Friday}\qquad\textbf{(B)}\ \text{Saturday}\qquad\textbf{(C)}\ \text{Sunday}\qquad\textbf{(D)}\ \text{Monday}\qquad\textbf{(E)}\ \text{Tuesday} </math> | <math> \textbf{(A)}\ \text{Friday}\qquad\textbf{(B)}\ \text{Saturday}\qquad\textbf{(C)}\ \text{Sunday}\qquad\textbf{(D)}\ \text{Monday}\qquad\textbf{(E)}\ \text{Tuesday} </math> | ||
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== Problem 13 == | == Problem 13 == | ||
− | An ''iterative average'' of the numbers 1, 2, 3, 4, and 5 is computed the following way. Arrange the five numbers in some order. Find the mean of the first two numbers, then find the mean of that with the third number, then the mean of that with the fourth number, and finally the mean of that with the fifth number. What is the difference between the largest and smallest possible values that can be obtained using this procedure? | + | An ''iterative average'' of the numbers <math>1</math>, <math>2</math>, <math>3</math>, <math>4</math>, and <math>5</math> is computed the following way. Arrange the five numbers in some order. Find the mean of the first two numbers, then find the mean of that with the third number, then the mean of that with the fourth number, and finally the mean of that with the fifth number. What is the difference between the largest and smallest possible values that can be obtained using this procedure? |
<math> \textbf{(A)}\ \frac{31}{16}\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ \frac{17}{8}\qquad\textbf{(D)}\ 3\qquad\textbf{(E)}\ \frac{65}{16} </math> | <math> \textbf{(A)}\ \frac{31}{16}\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ \frac{17}{8}\qquad\textbf{(D)}\ 3\qquad\textbf{(E)}\ \frac{65}{16} </math> | ||
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== Problem 16 == | == Problem 16 == | ||
− | Three runners start running simultaneously from the same point on a 500-meter circular track. They each run clockwise around the course maintaining constant speeds of 4.4, 4.8, and 5.0 meters per second. The runners stop once they are all together again somewhere on the circular course. How many seconds do the runners run? | + | Three runners start running simultaneously from the same point on a <math>500</math>-meter circular track. They each run clockwise around the course maintaining constant speeds of <math>4.4</math>, <math>4.8</math>, and <math>5.0</math> meters per second. The runners stop once they are all together again somewhere on the circular course. How many seconds do the runners run? |
<math> \textbf{(A)}\ 1,000\qquad\textbf{(B)}\ 1,250\qquad\textbf{(C)}\ 2,500\qquad\textbf{(D)}\ 5,000\qquad\textbf{(E)}\ 10,000 </math> | <math> \textbf{(A)}\ 1,000\qquad\textbf{(B)}\ 1,250\qquad\textbf{(C)}\ 2,500\qquad\textbf{(D)}\ 5,000\qquad\textbf{(E)}\ 10,000 </math> | ||
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== Problem 17 == | == Problem 17 == | ||
− | Let <math>a</math> and <math>b</math> be relatively prime integers with <math>a>b>0</math> and <math>\ | + | Let <math>a</math> and <math>b</math> be relatively prime positive integers with <math>a>b>0</math> and <math>\dfrac{a^3-b^3}{(a-b)^3} = \dfrac{73}{3}</math>. What is <math>a-b</math>? |
<math> \textbf{(A)}\ 1\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 3\qquad\textbf{(D)}\ 4\qquad\textbf{(E)}\ 5 </math> | <math> \textbf{(A)}\ 1\qquad\textbf{(B)}\ 2\qquad\textbf{(C)}\ 3\qquad\textbf{(D)}\ 4\qquad\textbf{(E)}\ 5 </math> | ||
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== Problem 18 == | == Problem 18 == | ||
− | The closed curve in the figure is made up of 9 congruent circular arcs each of length <math>\frac{2\pi}{3}</math>, where each of the centers of the corresponding circles is among the vertices of a regular hexagon of side 2. What is the area enclosed by the curve? | + | The closed curve in the figure is made up of <math>9</math> congruent circular arcs each of length <math>\frac{2\pi}{3}</math>, where each of the centers of the corresponding circles is among the vertices of a regular hexagon of side <math>2</math>. What is the area enclosed by the curve? |
<asy> | <asy> | ||
+ | size(5cm); | ||
defaultpen(fontsize(6pt)); | defaultpen(fontsize(6pt)); | ||
dotfactor=4; | dotfactor=4; | ||
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== Problem 19 == | == Problem 19 == | ||
− | Paula the painter and her two helpers each paint at constant, but different, rates. They always start at 8:00 AM, and all three always take the same amount of time to eat lunch. On Monday the three of them painted 50% of a house, quitting at 4:00 PM. On Tuesday, when Paula wasn't there, the two helpers painted only 24% of the house and quit at 2:12 PM. On Wednesday Paula worked by herself and finished the house by working until 7:12 P.M. How long, in minutes, was each day's lunch break? | + | Paula the painter and her two helpers each paint at constant, but different, rates. They always start at <math>8:00</math> AM, and all three always take the same amount of time to eat lunch. On Monday the three of them painted 50% of a house, quitting at <math>4:00</math> PM. On Tuesday, when Paula wasn't there, the two helpers painted only 24% of the house and quit at <math>2:12</math> PM. On Wednesday Paula worked by herself and finished the house by working until <math>7:12</math> P.M. How long, in minutes, was each day's lunch break? |
<math> \textbf{(A)}\ 30\qquad\textbf{(B)}\ 36\qquad\textbf{(C)}\ 42\qquad\textbf{(D)}\ 48\qquad\textbf{(E)}\ 60 </math> | <math> \textbf{(A)}\ 30\qquad\textbf{(B)}\ 36\qquad\textbf{(C)}\ 42\qquad\textbf{(D)}\ 48\qquad\textbf{(E)}\ 60 </math> | ||
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== Problem 20 == | == Problem 20 == | ||
− | A <math>3 | + | A <math>3 \times 3</math> square is partitioned into <math>9</math> unit squares. Each unit square is painted either white or black with each color being equally likely, chosen independently and at random. The square is then rotated <math>90\,^{\circ}</math> clockwise about its center, and every white square in a position formerly occupied by a black square is painted black. The colors of all other squares are left unchanged. What is the probability the grid is now entirely black? |
<math> \textbf{(A)}\ \frac{49}{512}\qquad\textbf{(B)}\ \frac{7}{64}\qquad\textbf{(C)}\ \frac{121}{1024}\qquad\textbf{(D)}\ \frac{81}{512}\qquad\textbf{(E)}\ \frac{9}{32} </math> | <math> \textbf{(A)}\ \frac{49}{512}\qquad\textbf{(B)}\ \frac{7}{64}\qquad\textbf{(C)}\ \frac{121}{1024}\qquad\textbf{(D)}\ \frac{81}{512}\qquad\textbf{(E)}\ \frac{9}{32} </math> | ||
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== Problem 21 == | == Problem 21 == | ||
− | Let points <math>A | + | Let points <math>A = (0 ,0 ,0)</math>, <math>B = (1, 0, 0)</math>, <math>C = (0, 2, 0)</math>, and <math>D = (0, 0, 3)</math>. Points <math>E</math>, <math>F</math>, <math>G</math>, and <math>H</math> are midpoints of line segments <math>\overline{BD},\text{ } \overline{AB}, \text{ } \overline {AC},</math> and <math>\overline{DC}</math> respectively. What is the area of <math>EFGH</math>? |
<math> \textbf{(A)}\ \sqrt{2}\qquad\textbf{(B)}\ \frac{2\sqrt{5}}{3}\qquad\textbf{(C)}\ \frac{3\sqrt{5}}{4}\qquad\textbf{(D)}\ \sqrt{3}\qquad\textbf{(E)}\ \frac{2\sqrt{7}}{3} </math> | <math> \textbf{(A)}\ \sqrt{2}\qquad\textbf{(B)}\ \frac{2\sqrt{5}}{3}\qquad\textbf{(C)}\ \frac{3\sqrt{5}}{4}\qquad\textbf{(D)}\ \sqrt{3}\qquad\textbf{(E)}\ \frac{2\sqrt{7}}{3} </math> | ||
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== Problem 22 == | == Problem 22 == | ||
− | The sum of the first <math>m</math> positive odd integers is 212 more than the sum of the first <math>n</math> positive even integers. What is the sum of all possible values of <math>n</math>? | + | The sum of the first <math>m</math> positive odd integers is <math>212</math> more than the sum of the first <math>n</math> positive even integers. What is the sum of all possible values of <math>n</math>? |
<math> \textbf{(A)}\ 255\qquad\textbf{(B)}\ 256\qquad\textbf{(C)}\ 257\qquad\textbf{(D)}\ 258\qquad\textbf{(E)}\ 259 </math> | <math> \textbf{(A)}\ 255\qquad\textbf{(B)}\ 256\qquad\textbf{(C)}\ 257\qquad\textbf{(D)}\ 258\qquad\textbf{(E)}\ 259 </math> | ||
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[[2012 AMC 10A Problems/Problem 25|Solution]] | [[2012 AMC 10A Problems/Problem 25|Solution]] | ||
+ | ==See also== | ||
+ | {{AMC10 box|year=2012|ab=A|before=[[2011 AMC 10B Problems]]|after=[[2012 AMC 10B Problems]]}} | ||
+ | * [[AMC 10]] | ||
+ | * [[AMC 10 Problems and Solutions]] | ||
+ | * [[2012 AMC 12A]] | ||
+ | * [[Mathematics competition resources]] | ||
{{MAA Notice}} | {{MAA Notice}} |
Latest revision as of 01:31, 22 December 2023
2012 AMC 10A (Answer Key) Printable versions: • AoPS Resources • PDF | ||
Instructions
| ||
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 |
Contents
- 1 Problem 1
- 2 Problem 2
- 3 Problem 3
- 4 Problem 4
- 5 Problem 5
- 6 Problem 6
- 7 Problem 7
- 8 Problem 8
- 9 Problem 9
- 10 Problem 10
- 11 Problem 11
- 12 Problem 12
- 13 Problem 13
- 14 Problem 14
- 15 Problem 15
- 16 Problem 16
- 17 Problem 17
- 18 Problem 18
- 19 Problem 19
- 20 Problem 20
- 21 Problem 21
- 22 Problem 22
- 23 Problem 23
- 24 Problem 24
- 25 Problem 25
- 26 See also
Problem 1
Cagney can frost a cupcake every seconds and Lacey can frost a cupcake every
seconds. Working together, how many cupcakes can they frost in
minutes?
Problem 2
A square with side length is cut in half, creating two congruent rectangles. What are the dimensions of one of these rectangles?
Problem 3
A bug crawls along a number line, starting at . It crawls to
, then turns around and crawls to
. How many units does the bug crawl altogether?
Problem 4
Let and
. What is the smallest possible degree measure for angle
?
Problem 5
Last year adult cats, half of whom were female, were brought into the Smallville Animal Shelter. Half of the adult female cats were accompanied by a litter of kittens. The average number of kittens per litter was
. What was the total number of cats and kittens received by the shelter last year?
Problem 6
The product of two positive numbers is . The reciprocal of one of these numbers is
times the reciprocal of the other number. What is the sum of the two numbers?
Problem 7
In a bag of marbles, of the marbles are blue and the rest are red. If the number of red marbles is doubled and the number of blue marbles stays the same, what fraction of the marbles will be red?
Problem 8
The sums of three whole numbers taken in pairs are ,
, and
. What is the middle number?
Problem 9
A pair of six-sided dice are labeled so that one die has only even numbers (two each of ,
, and
), and the other die has only odd numbers (two each of
,
, and
). The pair of dice is rolled. What is the probability that the sum of the numbers on the tops of the two dice is
?
Problem 10
Mary divides a circle into sectors. The central angles of these sectors, measured in degrees, are all integers and they form an arithmetic sequence. What is the degree measure of the smallest possible sector angle?
Problem 11
Externally tangent circles with centers at points and
have radii of lengths
and
, respectively. A line externally tangent to both circles intersects ray
at point
. What is
?
Problem 12
A year is a leap year if and only if the year number is divisible by (such as
) or is divisible by
but not
(such as
). The
th anniversary of the birth of novelist Charles Dickens was celebrated on February
,
, a Tuesday. On what day of the week was Dickens born?
Problem 13
An iterative average of the numbers ,
,
,
, and
is computed the following way. Arrange the five numbers in some order. Find the mean of the first two numbers, then find the mean of that with the third number, then the mean of that with the fourth number, and finally the mean of that with the fifth number. What is the difference between the largest and smallest possible values that can be obtained using this procedure?
Problem 14
Chubby makes nonstandard checkerboards that have squares on each side. The checkerboards have a black square in every corner and alternate red and black squares along every row and column. How many black squares are there on such a checkerboard?
Problem 15
Three unit squares and two line segments connecting two pairs of vertices are shown. What is the area of ?
![[asy] size(200); unitsize(2cm); defaultpen(linewidth(.8pt)+fontsize(10pt)); dotfactor=4; pair A=(0,0), B=(1,0); pair C=(0.8,-0.4); draw(A--(2,0)); draw((0,-1)--(2,-1)); draw((0,-2)--(1,-2)); draw(A--(0,-2)); draw(B--(1,-2)); draw((2,0)--(2,-1)); draw(A--(2,-1)); draw(B--(0,-2)); pair[] ps={A,B,C}; dot(ps); label("$A$",A,N); label("$B$",B,N); label("$C$",C,W); [/asy]](http://latex.artofproblemsolving.com/7/4/5/7455071b64017000edb58cc8b71022c0bfd9aefd.png)
Problem 16
Three runners start running simultaneously from the same point on a -meter circular track. They each run clockwise around the course maintaining constant speeds of
,
, and
meters per second. The runners stop once they are all together again somewhere on the circular course. How many seconds do the runners run?
Problem 17
Let and
be relatively prime positive integers with
and
. What is
?
Problem 18
The closed curve in the figure is made up of congruent circular arcs each of length
, where each of the centers of the corresponding circles is among the vertices of a regular hexagon of side
. What is the area enclosed by the curve?
Problem 19
Paula the painter and her two helpers each paint at constant, but different, rates. They always start at AM, and all three always take the same amount of time to eat lunch. On Monday the three of them painted 50% of a house, quitting at
PM. On Tuesday, when Paula wasn't there, the two helpers painted only 24% of the house and quit at
PM. On Wednesday Paula worked by herself and finished the house by working until
P.M. How long, in minutes, was each day's lunch break?
Problem 20
A square is partitioned into
unit squares. Each unit square is painted either white or black with each color being equally likely, chosen independently and at random. The square is then rotated
clockwise about its center, and every white square in a position formerly occupied by a black square is painted black. The colors of all other squares are left unchanged. What is the probability the grid is now entirely black?
Problem 21
Let points ,
,
, and
. Points
,
,
, and
are midpoints of line segments
and
respectively. What is the area of
?
Problem 22
The sum of the first positive odd integers is
more than the sum of the first
positive even integers. What is the sum of all possible values of
?
Problem 23
Adam, Benin, Chiang, Deshawn, Esther, and Fiona have internet accounts. Some, but not all, of them are internet friends with each other, and none of them has an internet friend outside this group. Each of them has the same number of internet friends. In how many different ways can this happen?
Problem 24
Let ,
, and
be positive integers with
such that
What is ?
Problem 25
Real numbers ,
, and
are chosen independently and at random from the interval
for some positive integer
. The probability that no two of
,
, and
are within 1 unit of each other is greater than
. What is the smallest possible value of
?
See also
2012 AMC 10A (Problems • Answer Key • Resources) | ||
Preceded by 2011 AMC 10B Problems |
Followed by 2012 AMC 10B Problems | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 | ||
All AMC 10 Problems and Solutions |
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions.