40 students in a class sold an average of 17 pens for charity. There were 8 more boys than girls in the class. The average number of pens sold by the boys was 13. Find the average number of pens sold by the girls.
| |
Girls |
Boys |
Total |
| Number |
1 u |
1 u + 8 |
40 |
| Value |
? |
13 |
17 |
| Total value |
368 |
312 |
680 |
Total number of pens sold
= 40 x 17
= 680
Number of girls = 1 u
Number of boys = 1 u + 8
1 u + 1 u + 8 = 40
2 u + 8 = 40
2 u = 40 - 8
2 u = 32
1 u = 32 ÷ 2 = 16
Number of boys in class
= 1 u + 8
= 16 + 8
= 24
Number of pens sold by boys
= 24 x 13
= 312
Number of pens sold by girls
= 680 - 312
= 368
Average number of pens sold by girls
= 368 ÷ 16
= 23
Answer(s): 23
