Difference between revisions of "2006 AMC 12B Problems"
m (+15) |
m ($ -> \textdollar + <asy>) |
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== Problem 4 == | == Problem 4 == | ||
− | Mary is about to pay for five items at the grocery store. The prices of the items are <math> | + | Mary is about to pay for five items at the grocery store. The prices of the items are <math>\textdollar7.99</math>, <math>\textdollar4.99</math>, <math>\textdollar2.99</math>, <math>\textdollar1.99</math>, and <math>\textdollar0.99</math>. Mary will pay with a twenty-dollar bill. Which of the following is closest to the percentage of the <math>\textdollar20.00</math> that she will receive in change? |
<math> | <math> | ||
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Rhombus <math> ABCD</math> is similar to rhombus <math> BFDE</math>. The area of rhombus <math> ABCD</math> is 24, and <math> \angle BAD \equal{} 60^\circ</math>. What is the area of rhombus <math> BFDE</math>? | Rhombus <math> ABCD</math> is similar to rhombus <math> BFDE</math>. The area of rhombus <math> ABCD</math> is 24, and <math> \angle BAD \equal{} 60^\circ</math>. What is the area of rhombus <math> BFDE</math>? | ||
− | <asy> | + | <asy> defaultpen(linewidth(0.7)+fontsize(11)); |
− | defaultpen(linewidth(0.7)); | + | pair A=origin, B=(2,0), C=(3, sqrt(3)), D=(1, sqrt(3)), E=(1, 1/sqrt(3)), F=(2, 2/sqrt(3)); |
− | pair A=origin, B=( | + | pair point=(3/2, sqrt(3)/2); |
− | draw( | + | draw(B--C--D--A--B--F--D--E--B); |
− | label("$A$", A, | + | label("$A$", A, dir(point--A)); |
− | label("$B$", B, | + | label("$B$", B, dir(point--B)); |
− | label("$C$", C, | + | label("$C$", C, dir(point--C)); |
− | label("$D$", D, | + | label("$D$", D, dir(point--D)); |
− | label("$E$", E, | + | label("$E$", E, dir(point--E)); |
− | label("$F$", F, | + | label("$F$", F, dir(point--F)); |
</asy> | </asy> | ||
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== Problem 14 == | == Problem 14 == | ||
− | Elmo makes <math>N</math> sandwiches for a fundraiser. For each sandwich he uses <math>B</math> globs of peanut butter at <math>4</math> cents per glob and <math>J</math> blobs of jam at <math>5</math> cents per glob. The cost of the peanut butter and jam to make all the sandwiches is <math> | + | Elmo makes <math>N</math> sandwiches for a fundraiser. For each sandwich he uses <math>B</math> globs of peanut butter at <math>4</math> cents per glob and <math>J</math> blobs of jam at <math>5</math> cents per glob. The cost of the peanut butter and jam to make all the sandwiches is <math>\textdollar 2.53</math>. Assume that <math>B</math>, <math>J</math> and <math>N</math> are all positive integers with <math>N>1</math>. What is the cost of the jam Elmo uses to make the sandwiches? |
− | < | + | <math> |
\mathrm{(A)}\ 1.05 | \mathrm{(A)}\ 1.05 | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ 1.85 | \mathrm{(E)}\ 1.85 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 14|Solution]] | [[2006 AMC 12B Problems/Problem 14|Solution]] | ||
== Problem 15 == | == Problem 15 == | ||
− | Circles with centers < | + | Circles with centers <math> O</math> and <math> P</math> have radii 2 and 4, respectively, and are externally tangent. Points <math> A</math> and <math> B</math> are on the circle centered at <math> O</math>, and points <math> C</math> and <math> D</math> are on the circle centered at <math> P</math>, such that <math> \overline{AD}</math> and <math> \overline{BC}</math> are common external tangents to the circles. What is the area of hexagon <math> AOBCPD</math>? |
{{image}} | {{image}} | ||
− | < | + | <math> \textbf{(A) } 18\sqrt {3} \qquad \textbf{(B) } 24\sqrt {2} \qquad \textbf{(C) } 36 \qquad \textbf{(D) } 24\sqrt {3} \qquad \textbf{(E) } 32\sqrt {2}</math> |
[[2006 AMC 12B Problems/Problem 15|Solution]] | [[2006 AMC 12B Problems/Problem 15|Solution]] | ||
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== Problem 16 == | == Problem 16 == | ||
− | Regular hexagon < | + | Regular hexagon <math>ABCDEF</math> has vertices <math>A</math> and <math>C</math> at <math>(0,0)</math> and <math>(7,1)</math>, respectively. What is its area? |
− | < | + | <math> |
\mathrm{(A)}\ 20\sqrt {3} | \mathrm{(A)}\ 20\sqrt {3} | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ 50 | \mathrm{(E)}\ 50 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 16|Solution]] | [[2006 AMC 12B Problems/Problem 16|Solution]] | ||
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== Problem 17 == | == Problem 17 == | ||
− | For a particular peculiar pair of dice, the probabilities of rolling < | + | For a particular peculiar pair of dice, the probabilities of rolling <math>1</math>, <math>2</math>, <math>3</math>, <math>4</math>, <math>5</math> and <math>6</math> on each die are in the ratio <math>1:2:3:4:5:6</math>. What is the probability of rolling a total of <math>7</math> on the two dice? |
− | < | + | <math> |
\mathrm{(A)}\ \frac 4{63} | \mathrm{(A)}\ \frac 4{63} | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ \frac 27 | \mathrm{(E)}\ \frac 27 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 17|Solution]] | [[2006 AMC 12B Problems/Problem 17|Solution]] | ||
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An object in the plane moves from one lattice point to another. At each step, the object may move one unit to the right, one unit to the left, one unit up, or one unit down. If the object starts at the origin and takes a ten-step path, how many different points could be the final point? | An object in the plane moves from one lattice point to another. At each step, the object may move one unit to the right, one unit to the left, one unit up, or one unit down. If the object starts at the origin and takes a ten-step path, how many different points could be the final point? | ||
− | < | + | <math> |
\mathrm{(A)}\ 120 | \mathrm{(A)}\ 120 | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ 231 | \mathrm{(E)}\ 231 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 18|Solution]] | [[2006 AMC 12B Problems/Problem 18|Solution]] | ||
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Mr. Jones has eight children of different ages. On a family trip his oldest child, who is 9, spots a license plate with a 4-digit number in which each of two digits appears two times. "Look, daddy!" she exclaims. "That number is evenly divisible by the age of each of us kids!" "That's right," replies Mr. Jones, "and the last two digits just happen to be my age." Which of the following is not the age of one of Mr. Jones's children? | Mr. Jones has eight children of different ages. On a family trip his oldest child, who is 9, spots a license plate with a 4-digit number in which each of two digits appears two times. "Look, daddy!" she exclaims. "That number is evenly divisible by the age of each of us kids!" "That's right," replies Mr. Jones, "and the last two digits just happen to be my age." Which of the following is not the age of one of Mr. Jones's children? | ||
− | < | + | <math> |
\mathrm{(A)}\ 4 | \mathrm{(A)}\ 4 | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ 8 | \mathrm{(E)}\ 8 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 19|Solution]] | [[2006 AMC 12B Problems/Problem 19|Solution]] | ||
== Problem 20 == | == Problem 20 == | ||
− | Let < | + | Let <math>x</math> be chosen at random from the interval <math>(0,1)</math>. What is the probability that |
− | < | + | <math>\lfloor\log_{10}4x\rfloor - \lfloor\log_{10}x\rfloor = 0</math>? |
− | Here < | + | Here <math>\lfloor x\rfloor</math> denotes the greatest integer that is less than or equal to <math>x</math>. |
− | < | + | <math> |
\mathrm{(A)}\ \frac 18 | \mathrm{(A)}\ \frac 18 | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ \frac 14 | \mathrm{(E)}\ \frac 14 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 20|Solution]] | [[2006 AMC 12B Problems/Problem 20|Solution]] | ||
== Problem 21 == | == Problem 21 == | ||
− | Rectange < | + | Rectange <math>ABCD</math> has area <math>2006</math>. An ellipse with area <math>2006\pi</math> passes through <math>A</math> and <math>C</math> and has foci at <math>B</math> and <math>D</math>. What is the perimeter of the rectangle? (The area of an ellipse is <math>ab\pi</math> where <math>2a</math> and <math>2b</math> are the lengths of the axes.) |
− | < | + | <math> |
\mathrm{(A)}\ \frac {16\sqrt {2006}}{\pi} | \mathrm{(A)}\ \frac {16\sqrt {2006}}{\pi} | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ \frac {32\sqrt {1003}}\pi | \mathrm{(E)}\ \frac {32\sqrt {1003}}\pi | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 21|Solution]] | [[2006 AMC 12B Problems/Problem 21|Solution]] | ||
== Problem 22 == | == Problem 22 == | ||
− | Suppose < | + | Suppose <math>a</math>, <math>b</math> and <math>c</math> are positive integers with <math>a+b+c=2006</math>, and <math>a!b!c!=m\cdot 10^n</math>, where <math>m</math> and <math>n</math> are integers and <math>m</math> is not divisible by <math>10</math>. What is the smallest possible value of <math>n</math>? |
− | < | + | <math> |
\mathrm{(A)}\ 489 | \mathrm{(A)}\ 489 | ||
\qquad | \qquad | ||
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\qquad | \qquad | ||
\mathrm{(E)}\ 501 | \mathrm{(E)}\ 501 | ||
− | <math> | + | </math> |
[[2006 AMC 12B Problems/Problem 22|Solution]] | [[2006 AMC 12B Problems/Problem 22|Solution]] | ||
== Problem 23 == | == Problem 23 == | ||
− | Isosceles < | + | Isosceles <math>\triangle ABC</math> has a right angle at <math>C</math>. Point <math>P</math> is inside <math>\triangle ABC</math>, such that <math>PA=11</math>, <math>PB=7</math>, and <math>PC=6</math>. Legs <math>\overline{AC}</math> and <math>\overline{BC}</math> have length <math>s=\sqrt{a+b\sqrt{2}{</math>, where <math>a</math> and <math>b</math> are positive integers. What is <math>a+b</math>? |
<asy> | <asy> | ||
− | pathpen = linewidth(0.7); | + | pathpen = linewidth(0.7); pointpen = black; |
pen f = fontsize(10); | pen f = fontsize(10); | ||
size(5cm); | size(5cm); |
Revision as of 22:25, 25 August 2011
Contents
[hide]- 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
What is ?
Problem 2
For real numbers and , define . What is ?
Problem 3
A football game was played between two teams, the Cougars and the Panthers. The two teams scored a total of 34 points, and the Cougars won by a margin of 14 points. How many points did the Panthers score?
Problem 4
Mary is about to pay for five items at the grocery store. The prices of the items are , , , , and . Mary will pay with a twenty-dollar bill. Which of the following is closest to the percentage of the that she will receive in change?
Problem 5
John is walking east at a speed of 3 miles per hour, while Bob is also walking east, but at a speed of 5 miles per hour. If Bob is now 1 mile west of John, how many minutes will it take for Bob to catch up to John?
Problem 6
Francesca uses 100 grams of lemon juice, 100 grams of sugar, and 400 grams of water to make lemonade. There are 25 calories in 100 grams of lemon juice and 386 calories in 100 grams of sugar. Water contains no calories. How many calories are in 200 grams of her lemonade.
Problem 7
Mr. and Mrs. Lopez have two children. When they get into their family car, two people sit in the front, and the other two sit in the back. Either Mr. Lopez or Mrs. Lopez must sit in the driver's seat. How many seating arrangements are possible?
Problem 8
The lines and intersect at the point . What is ?
Problem 9
How many even three-digit integers have the property that their digits, read left to right, are in strictly increasing order?
Problem 10
In a triangle with integer side lengths, one side is three times as long as a second side, and the length of the third side is 15. What is the greatest possible perimeter of the triangle?
Problem 11
Joe and JoAnn each bought 12 ounces of coffee in a 16-ounce cup. Joe drank 2 ounces of his coffee and then added 2 ounces of cream. JoAnn added 2 ounces of cream, stirred the coffee well, and then drank 2 ounces. What is the resulting ratio of the amount of cream in Joe's coffee to that in JoAnn's coffee?
Problem 12
The parabola has vertex and -intercept , where . What is ?
Problem 13
Rhombus is similar to rhombus . The area of rhombus is 24, and $\angle BAD \equal{} 60^\circ$ (Error compiling LaTeX. Unknown error_msg). What is the area of rhombus ?
Problem 14
Elmo makes sandwiches for a fundraiser. For each sandwich he uses globs of peanut butter at cents per glob and blobs of jam at cents per glob. The cost of the peanut butter and jam to make all the sandwiches is . Assume that , and are all positive integers with . What is the cost of the jam Elmo uses to make the sandwiches?
Problem 15
Circles with centers and have radii 2 and 4, respectively, and are externally tangent. Points and are on the circle centered at , and points and are on the circle centered at , such that and are common external tangents to the circles. What is the area of hexagon ?
An image is supposed to go here. You can help us out by creating one and editing it in. Thanks.
Problem 16
Regular hexagon has vertices and at and , respectively. What is its area?
Problem 17
For a particular peculiar pair of dice, the probabilities of rolling , , , , and on each die are in the ratio . What is the probability of rolling a total of on the two dice?
Problem 18
An object in the plane moves from one lattice point to another. At each step, the object may move one unit to the right, one unit to the left, one unit up, or one unit down. If the object starts at the origin and takes a ten-step path, how many different points could be the final point?
Problem 19
Mr. Jones has eight children of different ages. On a family trip his oldest child, who is 9, spots a license plate with a 4-digit number in which each of two digits appears two times. "Look, daddy!" she exclaims. "That number is evenly divisible by the age of each of us kids!" "That's right," replies Mr. Jones, "and the last two digits just happen to be my age." Which of the following is not the age of one of Mr. Jones's children?
Problem 20
Let be chosen at random from the interval . What is the probability that ? Here denotes the greatest integer that is less than or equal to .
Problem 21
Rectange has area . An ellipse with area passes through and and has foci at and . What is the perimeter of the rectangle? (The area of an ellipse is where and are the lengths of the axes.)
Problem 22
Suppose , and are positive integers with , and , where and are integers and is not divisible by . What is the smallest possible value of ?
Problem 23
Isosceles has a right angle at . Point is inside , such that , , and . Legs and have length $s=\sqrt{a+b\sqrt{2}{$ (Error compiling LaTeX. Unknown error_msg), where and are positive integers. What is ?
Problem 24
Let be the set of all points in the coordinate plane such that and . What is the area of the subset of for which ?
Problem 25
A sequence of non-negative integers is defined by the rule for . If , and , how many different values of are possible?