28 pupils in a class sold an average of 18 seashells for charity. There were 4 more boys than girls in the class. The average number of seashells sold by the boys was 12. Find the average number of seashells sold by the girls.
| |
Girls |
Boys |
Total |
| Number |
1 u |
1 u + 4 |
28 |
| Value |
? |
12 |
18 |
| Total value |
312 |
192 |
504 |
Total number of seashells sold
= 28 x 18
= 504
Number of girls = 1 u
Number of boys = 1 u + 4
1 u + 1 u + 4 = 28
2 u + 4 = 28
2 u = 28 - 4
2 u = 24
1 u = 24 ÷ 2 = 12
Number of boys in class
= 1 u + 4
= 12 + 4
= 16
Number of seashells sold by boys
= 16 x 12
= 192
Number of seashells sold by girls
= 504 - 192
= 312
Average number of seashells sold by girls
= 312 ÷ 12
= 26
Answer(s): 26
