36 students in a class sold an average of 17 marbles for charity. There were 6 more boys than girls in the class. The average number of marbles sold by the boys was 12. Find the average number of marbles sold by the girls.
| |
Girls |
Boys |
Total |
| Number |
1 u |
1 u + 6 |
36 |
| Value |
? |
12 |
17 |
| Total value |
360 |
252 |
612 |
Total number of marbles sold
= 36 x 17
= 612
Number of girls = 1 u
Number of boys = 1 u + 6
1 u + 1 u + 6 = 36
2 u + 6 = 36
2 u = 36 - 6
2 u = 30
1 u = 30 ÷ 2 = 15
Number of boys in class
= 1 u + 6
= 15 + 6
= 21
Number of marbles sold by boys
= 21 x 12
= 252
Number of marbles sold by girls
= 612 - 252
= 360
Average number of marbles sold by girls
= 360 ÷ 15
= 24
Answer(s): 24
