32 pupils in a class sold an average of 18 seashells for charity. There were 8 more boys than girls in the class. The average number of seashells sold by the boys was 15. Find the average number of seashells sold by the girls.
| |
Girls |
Boys |
Total |
| Number |
1 u |
1 u + 8 |
32 |
| Value |
? |
15 |
18 |
| Total value |
276 |
300 |
576 |
Total number of seashells sold
= 32 x 18
= 576
Number of girls = 1 u
Number of boys = 1 u + 8
1 u + 1 u + 8 = 32
2 u + 8 = 32
2 u = 32 - 8
2 u = 24
1 u = 24 ÷ 2 = 12
Number of boys in class
= 1 u + 8
= 12 + 8
= 20
Number of seashells sold by boys
= 20 x 15
= 300
Number of seashells sold by girls
= 576 - 300
= 276
Average number of seashells sold by girls
= 276 ÷ 12
= 23
Answer(s): 23
