25 students in a class sold an average of 20 seashells for charity. There were 5 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 + 5 |
25 |
| Value |
? |
12 |
20 |
| Total value |
320 |
180 |
500 |
Total number of seashells sold
= 25 x 20
= 500
Number of girls = 1 u
Number of boys = 1 u + 5
1 u + 1 u + 5 = 25
2 u + 5 = 25
2 u = 25 - 5
2 u = 20
1 u = 20 ÷ 2 = 10
Number of boys in class
= 1 u + 5
= 10 + 5
= 15
Number of seashells sold by boys
= 15 x 12
= 180
Number of seashells sold by girls
= 500 - 180
= 320
Average number of seashells sold by girls
= 320 ÷ 10
= 32
Answer(s): 32
