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TIMO - 2019 - Grade 7 - Heat Round - Paper 3

Question 1

There are 5 pieces of white chopsticks, 7 pieces of yellow chopsticks and 9 pieces of blue chopsticks mixed together. If you want to get 3 pairs of chopsticks with same colours in the dark, at least how many pieces of chopsticks are needed to be taken?

Question 2

Robert goes east for 21km, then goes south for 28km. How many km is he now from the original position?

Question 3

Given $A:B=3:7$, $B:C=5:11$, $C:D=2:3$ and $A+B+C+D=970$, find $B$.

Question 4

Find the average of these ten numbers: 2015, 2026, 2006, 2005, 2018, 1989, 2046, 2039, 2007, 2029.

Question 5

There are some chickens and rabbits in a cage. The number of chickens is five times as the number of rabbits. The total number of chicken legs is 78 more than that of rabbit. How many rabbit(s) is / are there?

Question 7

Given $\lvert x+2\rvert+(y-3)^2=0$, calculate $(x+y)+(x+y)^2+\cdots+(x+y)^{2018}$.

Question 8

How many negative integer solutions $x$ satisfy $7x+24>-27$?

Question 9

Given positive real numbers $a,b$ with $a^2-b^2=96$ and $a+b=12$, find $a-b$.

Question 11

Find the sum of all positive factors of 1014.

Question 12

Given $x>0$ and $x+\frac1x=5$, find $x^2+\frac1{x^2}$.

Question 13

Find the last digit of $A=1+4+9+16+25+\cdots+529+576+625$.

Question 14

When a 4-digit number is divided by 4, 6 or 8, the remainder is 3. What is the smallest possible value of that 4-digit number?

Question 15

Given rational $x>0$ with $x=2+\frac3{2+\frac3{2+\cdots}}$, find $x$.

Question 16

$E,F$ are the midpoints of $AB,BC$ respectively. The area of parallelogram $ABCD$ is 240. Find the area of triangle $DEF$.

Question illustration

Question 17

$M(-5,-5)$ is the midpoint of $A(-3,1)$ and $B(x,y)$. Find $x+y$.

Question 18

Some cubes with side length 1cm are combined according to the pattern shown below. If there are 19 layers, find the surface area in cm².

Question illustration

Question 19

The hypotenuse of a right-angled triangle is 20, find the maximum area of the triangle.

Question 20

A circle has radius 77, and its circumference equals the area of a square. Find the side length of the square. Take $\pi=\frac{22}{7}$.