There are 181 students in a hall.
38 of the boys and
47 of the girls wear caps, there are 109 students in the hall who do not wear caps. How many girls do not wear caps?
| |
Boys |
Girls |
Total |
| Do not wear caps |
5 u |
3 p |
109 |
| Wear caps |
3 u |
4 p |
72 |
| Total |
8 u |
7 p |
181 |
Number of students who wear caps
= 181 - 109
= 72
5 u + 3 p = 109 --- (1)
3 u + 4 p = 72 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 327 --- (3)
(2)
x 5 15 u + 20 p = 360 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 360 - 327
20 p - 9 p = 33
11 p = 33
1 p = 33 ÷ 11 = 3
Number of girls who do not wear caps
= 3 p
= 3 x 3
= 9
Answer(s): 9
