Question

90 juniors took different SAT-II tests. 40% more students took Chemistry than History, and 50% more students took Math than Chemistry. How many students took each test?

___ Students took History Test
___Students took Chemistry Test
___Students took Math Test

Answer 1

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

Explanation:

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

Answer 2

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test

Explanation:

Let

x ----> Students that took History Test

y ---> Students that took Chemistry Test

z ----> Students that took Math Test

we know that

x+y+z=90 -----> equation A

y=1.40x -----> x=y/1.40 -----> equation B

z=1.50y -----> equation C

substitute equation B and equation C in equation A and solve for y

(y/1.40)+y+1.50y=90

Multiply both sides by 1.40

y+1.40y+2.1y=126

4.5y=126

y=28

Find the value of x

x=y/1.40 -----> x=28/1.4=20

Find the value of z

z=1.50y ----> z=1.50(28)=42

therefore

20 Students took History Test

28 Students took Chemistry Test

42 Students took Math Test