# 2021 April MIMC 10

## 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

## Problem 1

What is the sum of ?

## Problem 2

Okestima is reading a page book. He reads a page every minutes, and he pauses minutes when he reaches the end of page 90 to take a break. He does not read at all during the break. After, he comes back with food and this slows down his reading speed. He reads one page in minutes. If he starts to read at , when does he finish the book?

## Problem 3

Find the number of real solutions that satisfy the equation .

## Problem 4

Stiskwey wrote all the possible permutations of the letters ( is different from ). How many such permutations are there?

## Problem 5

5. Given , Find .

## Problem 6

A worker cuts a piece of wire into two pieces. The two pieces, and , enclose an equilateral triangle and a square with equal area, respectively. The ratio of the length of to the length of can be expressed as in the simplest form. Find .

## Problem 7

Find the least integer such that where denotes in base-.

## Problem 8

In the morning, Mr.Gavin always uses his alarm to wake him up. The alarm is special. It always rings in a cycle of ten rings. The first ring lasts second, and each ring after lasts twice the time than the previous ring. Given that Mr.Gavin has an equal probability of waking up at any time, what is the probability that Mr.Gavin wakes up and end the alarm during the tenth ring?

## Problem 9

Find the largest number in the choices that divides .

## Problem 10

If and , find .

## Problem 11

How many factors of is a perfect cube or a perfect square?

## Problem 12

Given that , what is ?

## Problem 13

Given that Giant want to put green identical balls into different boxes such that each box contains at least two balls, and that no box can contain or more balls. Find the number of ways that Giant can accomplish this.

## Problem 14

James randomly choose an ordered pair which both and are elements in the set , and are not necessarily distinct, and all of the equations: are divisible by . Find the probability that James can do so.

## Problem 15

Paul wrote all positive integers that's less than and wrote their base representation. He randomly choose a number out the list. Paul insist that he want to choose a number that had only and as its digits, otherwise he will be depressed and relinquishes to do homework. How many numbers can he choose so that he can finish his homework?

## Problem 16

Find the number of permutations of such that at exactly two s are adjacent, and the s are not adjacent.

## Problem 17

The following expression can be expressed as which both and are relatively prime positive integers. Find .

## Problem 18

What can be a description of the set of solutions for this: ?

Two overlapping circles with each area .

Four not overlapping circles with each area .

There are two overlapping circles on the right of the -axis with each area and the intersection area of two overlapping circles on the left of the -axis with each area .

Four overlapping circles with each area .

There are two overlapping circles on the right of the -axis with each area and the intersection area of two overlapping circles on the left of the -axis with each area .

## Problem 19

can be expressed as in base which is a positive integer. Find the sum of the digits of .

## Problem 20

Given that . Given that the product of the even divisors is , and the product of the odd divisors is . Find .

## Problem 21

How many solutions are there for the equation . (Recall that is the largest integer less than , and is the smallest integer larger than .)

## Problem 22

In the diagram, is a square with area . is a diagonal of square . Square has area . Given that point bisects line segment , and is a line segment. Extend to meet diagonal and mark the intersection point . In addition, is drawn so that . can be represented as where are not necessarily distinct integers. Given that , and does not have a perfect square factor. Find .

## Problem 23

On a coordinate plane, point denotes the origin which is the center of the diamond shape in the middle of the figure. Point has coordinate , and point , , and are formed through , , and rotation about the origin , respectively. Quarter circle (formed by the arc and line segments and ) has area . Furthermore, another quarter circle formed by arc and line segments , is formed through a reflection of sector across the line . The small diamond centered at is a square, and the area of the little square is . Let denote the area of the shaded region, and denote the sum of the area of the regions (formed by side , arc , and side ), (formed by side , arc , and side ) and sectors and . Find in the simplest radical form.

## Problem 24

One semicircle is constructed with diameter and let the midpoint of be . Construct a point on the side of segment (closer to segment than arc ) such that the distance from to is , and that is perpendicular to the diameter . Three more such congruent semicircles are formed through multiple rotations around the point . Name the endpoints of the diameters , , , , , in a circular direction from to . Another four congruent semicircles are constructed with diameters , and that the distance from the diameters to the point are less than the distance from the arcs to the point . Connect , , , , and . Find the ratio of the area of the pentagon to the total area of the shape formed by arcs , , , , , , , .