193 children are in a school.
14 of the boys and
19 of the girls wear glasses.
32 children wear glasses.
- How many boys are there?
- How many girls are there?
- How many children do not wear glasses?
|
Number |
Boys |
Girls |
Total |
193 |
4 u |
9 p |
Wear glasses |
32 |
1 u |
1 p |
No glasses |
|
3 u |
8 p |
(a)
Number of boys = 4 u
Number of girls = 9 p
4 u + 9 p = 193 --- (1)
1 u + 1 p = 32 --- (2)
(2)
x 4 4 u + 4 p = 128 --- (3)
(1) - (3)
(4 u + 9 p) - (4 u + 4 p) = 193 - 128
4 u + 9 p - 4 u - 4 p = 65
5 p = 65
1 p = 65 ÷ 5 = 13
Substitute 1 p = 13 into (2).
1 u + 1 p = 32
1 u + 13 = 32
1 u = 32 - 13 = 19
Number of boys
= 4 u
= 4 x 19
= 76
(b)
Number of girls
= 9 p
= 9 x 13
= 117
(c)
Number of boys who do not wear glasses
= 4 u - 1 u
= 3 u
Number of girls who do not wear glasses
= 9 p - 1 p
= 8 p
Number of children who do not wear glasses
= 193 - 32
= 161
Answer(s): (a) 76; (b) 117; (c) 161