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Difference between revisions of "2005 Alabama ARML TST Problems"

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[[2005 Alabama ARML TST Problems/Problem 2 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 2 | Solution]]
 
==Problem 3==
 
==Problem 3==
−
The difference between the areas of the circumcircle and incircle of an equilateral triangle is <math>\displaystyle 300\pi</math> square units. Find the number of units in the length of a side of the triangle.
+
The difference between the areas of the circumcircle and incircle of an equilateral triangle is <math>300\pi</math> square units. Find the number of units in the length of a side of the triangle.
  
 
[[2005 Alabama ARML TST Problems/Problem 3 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 3 | Solution]]
 
==Problem 4==
 
==Problem 4==
−
For how many ordered pairs of digits <math>\displaystyle (A,B)</math> is <math>\displaystyle 2AB8</math> a multiple of 12?
+
For how many ordered pairs of digits <math>(A,B)</math> is <math>2AB8</math> a multiple of 12?
  
 
[[2005 Alabama ARML TST Problems/Problem 4 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 4 | Solution]]
 
==Problem 5==
 
==Problem 5==
−
A <math>\displaystyle 2\times 2</math> square grid is constructed with four <math>\displaystyle 1\times 1</math> squares. The square on the upper left is labeled <i>A</i>, the square on the upper right is labeled <i>B</i>, the square in the lower left is labled <i>C</i>, and the square on the lower right is labeled <i>D</i>. The four squares are to be painted such that 2 are blue, 1 is red, and 1 is green. In how many ways can this be done?
+
A <math>2\times 2</math> square grid is constructed with four <math>1\times 1</math> squares. The square on the upper left is labeled <i>A</i>, the square on the upper right is labeled <i>B</i>, the square in the lower left is labled <i>C</i>, and the square on the lower right is labeled <i>D</i>. The four squares are to be painted such that 2 are blue, 1 is red, and 1 is green. In how many ways can this be done?
  
 
[[2005 Alabama ARML TST Problems/Problem 5 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 5 | Solution]]
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[[2005 Alabama ARML TST Problems/Problem 6 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 6 | Solution]]
 
==Problem 7==
 
==Problem 7==
−
Find the sum of the infinite series: <center><math>\displaystyle 3+\frac{11}4+\frac 94 + \cdots + \frac{n^2+2n+3}{2^n}+\cdots</math>.</center>
+
Find the sum of the infinite series: <center><math>3+\frac{11}4+\frac 94 + \cdots + \frac{n^2+2n+3}{2^n}+\cdots</math>.</center>
  
 
[[2005 Alabama ARML TST Problems/Problem 7 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 7 | Solution]]
 
==Problem 8==
 
==Problem 8==
−
Find the number of ordered pairs of integers <math>\displaystyle (x,y)</math> which satisfy <center><math>x^2+4xy+y^2=21</math>.</center>
+
Find the number of ordered pairs of integers <math>(x,y)</math> which satisfy <center><math>x^2+4xy+y^2=21</math>.</center>
  
 
[[2005 Alabama ARML TST Problems/Problem 8 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 8 | Solution]]
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[[2005 Alabama ARML TST Problems/Problem 10 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 10 | Solution]]
 
==Problem 11==
 
==Problem 11==
−
In concave hexagon <i>ABCDEF</i>, <math>\displaystyle \angle  A = \angle B = \angle C = 90^\circ</math>, <math>\angle D = 100^\circ</math>, and <math>\displaystyle \angle F = 80^\circ</math>. Also, <i>CD=FA</i>, <i>AB</i>=7, <i>BC</i>=9, and <math>\displaystyle EF+DE=12</math>. Compute the area of the hexagon.
+
In concave hexagon <math>ABCDEF</math>, <math>\angle  A = \angle B = \angle C = 90^\circ</math>, <math>\angle D = 100^\circ</math>, and <math>\angle F = 80^\circ</math>. Also, <math>CD=FA</math>, <math>AB=7</math>, <math>BC=9</math>, and <math>EF+DE=12</math>. Compute the area of the hexagon.
  
 
[[2005 Alabama ARML TST Problems/Problem 11 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 11 | Solution]]
 +
 
==Problem 12==
 
==Problem 12==
−
Find the number of ordered pairs of positive integers <math>\displaystyle (a,b,c,d)</math> that satisfy the following equation:<center><math>\displaystyle a+b+c+d=12</math>.</center>
+
Find the number of ordered pairs of positive integers <math>(a,b,c,d)</math> that satisfy the following equation:<center><math>a+b+c+d=12</math>.</center>
  
 
[[2005 Alabama ARML TST Problems/Problem 12 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 12 | Solution]]
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[[2005 Alabama ARML TST Problems/Problem 13 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 13 | Solution]]
 
==Problem 14==
 
==Problem 14==
−
Find the fourth smallest possible value of <math>\displaystyle x+y</math> where <i>x</i> and <i>y</i> are positive integers that satisfy the following equation:<center><math>x^2-2y^2=1</math>.</center>
+
Find the fourth smallest possible value of <math>x+y</math> where <i>x</i> and <i>y</i> are positive integers that satisfy the following equation:<center><math>x^2-2y^2=1</math>.</center>
  
 
[[2005 Alabama ARML TST Problems/Problem 14 | Solution]]
 
[[2005 Alabama ARML TST Problems/Problem 14 | Solution]]
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==See also==
 
==See also==
−
[[Alabama ARML TST]]
+
* [[Alabama ARML TST]]
−
[[Alabama ARML]]
+
* [[Alabama ARML]]
−
[[Alabama Math Contests]]
+
* [[Alabama Math Contests]]

Latest revision as of 13:06, 1 March 2008

Problem 1

Two six-sided dice are constructed such that each face is equally likely to show up when rolled. The numbers on the faces of one of the dice are 1, 3, 4, 5, 6, and 8. The numbers on the faces of the other die are 1, 2, 2, 3, 3, and 4. Find the probability of rolling a sum of 9 with these two dice.

Solution

Problem 2

A large cube is painted green and then chopped up into 64 smaller congruent cubes. How many of the smaller cubes have at least one face painted green?

Solution

Problem 3

The difference between the areas of the circumcircle and incircle of an equilateral triangle is $300\pi$ square units. Find the number of units in the length of a side of the triangle.

Solution

Problem 4

For how many ordered pairs of digits $(A,B)$ is $2AB8$ a multiple of 12?

Solution

Problem 5

A $2\times 2$ square grid is constructed with four $1\times 1$ squares. The square on the upper left is labeled A, the square on the upper right is labeled B, the square in the lower left is labled C, and the square on the lower right is labeled D. The four squares are to be painted such that 2 are blue, 1 is red, and 1 is green. In how many ways can this be done?

Solution

Problem 6

How many of the positive divisors of 3,240,000 are perfect cubes?

Solution

Problem 7

Find the sum of the infinite series:

$3+\frac{11}4+\frac 94 + \cdots + \frac{n^2+2n+3}{2^n}+\cdots$.

Solution

Problem 8

Find the number of ordered pairs of integers $(x,y)$ which satisfy

$x^2+4xy+y^2=21$.

Solution

Problem 9

A square is inscribed in a circle of diameter 12. Two vertices of a triangle are also vertices of one side of the square. The other vertex of the triangle is on the circle. Find the largest possible area of the triangle.

Solution

Problem 10

When Jon Stewart walks up stairs he takes one or two steps at a time. His stepping sequence is not necessarily regular. He might step up one step, then two, then two again, then one, then one, and then two in order to climb up a total of 9 steps. In how many ways can Jon walk up a 14 step stairwell?

Solution

Problem 11

In concave hexagon $ABCDEF$, $\angle A = \angle B = \angle C = 90^\circ$, $\angle D = 100^\circ$, and $\angle F = 80^\circ$. Also, $CD=FA$, $AB=7$, $BC=9$, and $EF+DE=12$. Compute the area of the hexagon.

Solution

Problem 12

Find the number of ordered pairs of positive integers $(a,b,c,d)$ that satisfy the following equation:

$a+b+c+d=12$.

Solution

Problem 13

There is one natural number with exactly 6 positive divisors, the sum of whose reciprocals is 2. Find that natural number.

Solution

Problem 14

Find the fourth smallest possible value of $x+y$ where x and y are positive integers that satisfy the following equation:

$x^2-2y^2=1$.

Solution

Problem 15

Virginia has a pair of fair 8 sided dice with faces numbered 1-8 on each die. Montana has a pair of fair 8 sided dice with faces numbered with positive integers in such a way that when her pair of dice is rolled, the probability of any particular sum occurring is the same as when Virginia rolls her dice. The largest number on any face of either of Montana's dice is 11. Find the sum of the numbers on the faces of Montana's die whose faces are all less than 11.

Solution

See also

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