Page 156 - ArithBook5thEd ~ BCC

5.2.3 Exercises

Solve the following proportions.
1 3
1. =
5 x
15 2
2. =
y 3
100 20
3. =
5 y

A 5
4. =
9 3
11 1
5. =
B 2
5 c
6. =
3 6
s 4
7. =
3 13
1.2 A
8. =
7 0.84
P 75
9. =
100 125

3 1 4
10. 5 =
x 2 1
2

5.3 Percent problems

Any problem involving percent can be stated (or restated) in the form

“A is P percent of B”

where one of the numbers A, B or P is unknown. We can make this into a mathematical equation by
making the following “translations:”

“is” ←→ =
P
“P percent” ←→
100
“of” ←→ ×

This gives us the equation
P
A = × B.
100
If we divide both sides of the equation by B, we obtain the proportion in the box below.

Page 156