Difference between revisions of "2016 AIME I Problems"

(Problem 13)
(Problem 8)
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==Problem 8==
 
==Problem 8==
 
For a permutation <math>p = (a_1,a_2,\ldots,a_9)</math> of the digits <math>1,2,\ldots,9</math>, let <math>s(p)</math> denote the sum of the three <math>3</math>-digit numbers <math>a_1a_2a_3</math>, <math>a_4a_5a_6</math>, and <math>a_7a_8a_9</math>. Let <math>m</math> be the minimum value of <math>s(p)</math> subject to the condition that the units digit of <math>s(p)</math> is <math>0</math>. Let <math>n</math> denote the number of permutations <math>p</math> with <math>s(p) = m</math>. Find <math>|m - n|</math>.
 
For a permutation <math>p = (a_1,a_2,\ldots,a_9)</math> of the digits <math>1,2,\ldots,9</math>, let <math>s(p)</math> denote the sum of the three <math>3</math>-digit numbers <math>a_1a_2a_3</math>, <math>a_4a_5a_6</math>, and <math>a_7a_8a_9</math>. Let <math>m</math> be the minimum value of <math>s(p)</math> subject to the condition that the units digit of <math>s(p)</math> is <math>0</math>. Let <math>n</math> denote the number of permutations <math>p</math> with <math>s(p) = m</math>. Find <math>|m - n|</math>.
 +
 
[[2016 AIME I Problems/Problem 8 | Solution]]
 
[[2016 AIME I Problems/Problem 8 | Solution]]
  

Revision as of 15:22, 4 March 2016

2016 AIME I (Answer Key)
Printable version | AoPS Contest CollectionsPDF

Instructions

  1. This is a 15-question, 3-hour examination. All answers are integers ranging from $000$ to $999$, inclusive. Your score will be the number of correct answers; i.e., there is neither partial credit nor a penalty for wrong answers.
  2. No aids other than scratch paper, graph paper, ruler, compass, and protractor are permitted. In particular, calculators and computers are not permitted.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Problem 1

Solution

Problem 2

Solution

Problem 3

Solution

Problem 4

Solution

Problem 5

Solution

Problem 6

In $\triangle ABC$ let $I$ be the center of the inscribed circle, and let the bisector of $\angle ACB$ intersect $\overline{AB}$ at $L$. The line through $C$ and $L$ intersects the circumscribed circle of $\triangle ABC$ at the two points $C$ and $D$. If $LI=2$ and $LD=3$, then $IC= \frac{p}{q}$, where $p$ and $q$ are relatively prime positive integers. Find $p+q$.

Solution

Problem 7

Solution

Problem 8

For a permutation $p = (a_1,a_2,\ldots,a_9)$ of the digits $1,2,\ldots,9$, let $s(p)$ denote the sum of the three $3$-digit numbers $a_1a_2a_3$, $a_4a_5a_6$, and $a_7a_8a_9$. Let $m$ be the minimum value of $s(p)$ subject to the condition that the units digit of $s(p)$ is $0$. Let $n$ denote the number of permutations $p$ with $s(p) = m$. Find $|m - n|$.

Solution

Problem 9

Solution

Problem 10

A strictly increasing sequence of positive integers $a_1$, $a_2$, $a_3$, $\cdots$ has the property that for every positive integer $k$, the subsequence $a_{2k-1}$, $a_{2k}$, $a_{2k+1}$ is geometric and the subsequence $a_{2k}$, $a_{2k+1}$, $a_{2k+2}$ is arithmetic. Suppose that $a_{13} = 2016$. Find $a_1$.

Solution

Problem 11

Let $P(x)$ be a nonzero polynomial such that $(x-1)P(x+1)=(x+2)P(x)$ for every real $x$, and $\left(P(2)\right)^2 = P(3)$. Then $P(\tfrac72)=\tfrac{m}{n}$, where $m$ and $n$ are relatively prime positive integers. Find $m + n$.

Solution

Problem 12

Solution

Problem 13

Freddy the frog is jumping around the coordinate plane searching for a river, which lies on the horizontal line $y = 24$. A fence is located at the horizontal line $y = 0$. On each jump Freddy randomly chooses a direction parallel to one of the coordinate axes and moves one unit in that direction. When he is at a point where $y=0$, with equal likelihoods he chooses one of three directions where he either jumps parallel to the fence or jumps away from the fence, but he never chooses the direction that would have him cross over the fence to where $y < 0$. Freddy starts his search at the point $(0, 21)$ and will stop once he reaches a point on the river. Find the expected number of jumps it will take Freddy to reach the river. Solution

Problem 14

Solution

Problem 15

Solution

2016 AIME I (ProblemsAnswer KeyResources)
Preceded by
2015 AIME II
Followed by
2016 AIME II
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
All AIME Problems and Solutions

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