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AMO 2027 Grades 6-7 SET 30 - Self-study

Question 1

Choose a numerator and a denominator from $1,2,3,4,5,6,7,8,9,10$. Many resulting fractions are equal after reduction. How many distinct reduced fractions are strictly greater than $1/2$ and strictly less than $1$?

**Input:** Enter the integer only, without units.

Question 2

Jericho has stickers. Grouping them in piles of 6 leaves 5 stickers, in piles of 22 leaves 21, and in piles of 14 leaves 13. What is the least possible number of stickers?

**Input:** Choose one option.
  1. 461
  2. 462
  3. 923
  4. 924
  5. 131

Question 3

Look at the distance–time graph. Which listed interval has the highest average rate of change of distance? The vertical axis is distance (km); the horizontal axis is time (minutes).

Question illustration

**Input:** Choose one option.
  1. A to B
  2. B to C
  3. A to C
  4. D to E
  5. E to F

Question 4

Three faces of a rectangular box have areas $30\text{ cm}^2$, $18\text{ cm}^2$ and $15\text{ cm}^2$. What is its volume in $\text{cm}^3$?

Question illustration

**Input:** Choose one option.
  1. 30
  2. 18
  3. 15
  4. 90
  5. 60

Question 5

Three brothers have a total age of 32 years. The oldest is twice as old as the youngest. The two older brothers differ in age by 3 years. How old is the youngest?

**Input:** Choose one option.
  1. 5
  2. 7
  3. 9
  4. 11
  5. 13

Question 6

The same symbol always has the same value. Given
$$\square+\triangle+\diamond=60,\quad \triangle+\diamond+\star=44,$$
$$\diamond+\star+\square=52,\quad\triangle+\diamond+\star+\square=74,$$
find $\star+\square+\triangle$.

Question illustration

**Input:** Choose one option.
  1. 30
  2. 22
  3. 44
  4. 66
  5. 11

Question 7

Find the greatest positive integer that divides 266, 516 and 741 with the same remainder in each case.

**Input:** Enter the integer only, without units.

Question 8

For example, $2^5=2\times2\times2\times2\times2$. If $4096=a^b$, find the sum of all possible values of $a$, where $a$ is a positive integer and $b$ is a whole number greater than 1.

**Input:** Choose one option.
  1. 14
  2. 30
  3. 94
  4. 4190
  5. 4188

Question 9

The product of two or more consecutive positive integers is a six-digit palindrome whose first two digits are 47. What is the largest integer in the product? A palindrome reads the same backwards and forwards. Use positive integers, as intended by the source.

**Input:** Enter the integer only, without units.

Question 10

A lattice point has integer coordinates. Form the set of points $(a,b)$ where both $a$ and $b$ are positive integers. How many of these points lie on the line $y=-4x+8$?

**Input:** Enter the integer only, without units.

Question 11

Four sisters paint at the same constant rate and take turns, with no overlap or gaps. Alice finishes $1/4$ of the job; then Beth finishes $2/3$ of what is left; then Cathy finishes $3/4$ of the new remainder. Dee completes the last part in 20 minutes. How many minutes does the entire job take?

**Input:** Enter the integer only, without units.

Question 12

What is the value of $0^1$?

**Input:** Choose one option.
  1. 0
  2. 1
  3. $\infty$
  4. 10
  5. None of these

Question 13

In the cryptarithm $\overline{TIC}+\overline{TAC}+\overline{TOE}=\overline{WIN}$, different letters represent different decimal digits and equal letters represent the same digit. Given $A=5$ and $O=4$, find the greatest possible value of $\overline{WIN}$. The leading digits $T,W$ are nonzero.

Question illustration

**Input:** Enter the integer only, without units.

Question 14

A mother makes $x$ cakes in 2 hours and $y$ pizzas in 3 hours. How many cakes and pizzas altogether can she make in 6 hours? Assume she makes both together, each at the same constant rate as when making it separately.

**Input:** Choose one option.
  1. $6\left(\frac{x}{2}+\frac{y}{3}\right)$
  2. $6\left(\frac{y}{2}+\frac{x}{3}\right)$
  3. $6(2x+3y)$
  4. $6(3x+2y)$
  5. 30

Question 15

The first 73 odd whole numbers are written down. How many times does the digit 3 appear? Count every occurrence, so a number with two 3s contributes twice.

**Input:** Choose one option.
  1. 23
  2. 24
  3. 25
  4. 26
  5. 27