24 pupils in a class sold an average of 15 pens for charity. There were 8 more girls than boys in the class. The average number of pens sold by the girls was 14. Find the average number of pens sold by the boys.
| |
Boys |
Girls |
Total |
| Number |
1 u |
1 u + 8 |
24 |
| Value |
? |
14 |
15 |
| Total value |
136 |
224 |
360 |
Total number of pens sold
= 24 x 15
= 360
Number of boys = 1 u
Number of girls = 1 u + 8
1 u + 1 u + 8 = 24
2 u + 8 = 24
2 u = 24 - 8
2 u = 16
1 u = 16 ÷ 2 = 8
Number of girls in class
= 1 u + 8
= 8 + 8
= 16
Number of pens sold by girls
= 16 x 14
= 224
Number of pens sold by boys
= 360 - 224
= 136
Average number of pens sold by boys
= 136 ÷ 8
= 17
Answer(s): 17
