36 children in a class sold an average of 18 marbles for charity. There were 4 more girls than boys in the class. The average number of marbles sold by the girls was 14. Find the average number of marbles sold by the boys.
| |
Boys |
Girls |
Total |
| Number |
1 u |
1 u + 4 |
36 |
| Value |
? |
14 |
18 |
| Total value |
368 |
280 |
648 |
Total number of marbles sold
= 36 x 18
= 648
Number of boys = 1 u
Number of girls = 1 u + 4
1 u + 1 u + 4 = 36
2 u + 4 = 36
2 u = 36 - 4
2 u = 32
1 u = 32 ÷ 2 = 16
Number of girls in class
= 1 u + 4
= 16 + 4
= 20
Number of marbles sold by girls
= 20 x 14
= 280
Number of marbles sold by boys
= 648 - 280
= 368
Average number of marbles sold by boys
= 368 ÷ 16
= 23
Answer(s): 23
