188 people are in a school.
14 of the females and
18 of the males wear glasses.
40 people wear glasses.
- How many females are there?
- How many males are there?
- How many people do not wear glasses?
|
Number |
Females |
Males |
Total |
188 |
4 u |
8 p |
Wear glasses |
40 |
1 u |
1 p |
No glasses |
|
3 u |
7 p |
(a)
Number of females = 4 u
Number of males = 8 p
4 u + 8 p = 188 --- (1)
1 u + 1 p = 40 --- (2)
(2)
x 4 4 u + 4 p = 160 --- (3)
(1) - (3)
(4 u + 8 p) - (4 u + 4 p) = 188 - 160
4 u + 8 p - 4 u - 4 p = 28
4 p = 28
1 p = 28 ÷ 4 = 7
Substitute 1 p = 7 into (2).
1 u + 1 p = 40
1 u + 7 = 40
1 u = 40 - 7 = 33
Number of females
= 4 u
= 4 x 33
= 132
(b)
Number of males
= 8 p
= 8 x 7
= 56
(c)
Number of females who do not wear glasses
= 4 u - 1 u
= 3 u
Number of males who do not wear glasses
= 8 p - 1 p
= 7 p
Number of people who do not wear glasses
= 188 - 40
= 148
Answer(s): (a) 132; (b) 56; (c) 148