24 pupils in a class sold an average of 20 pens for charity. There were 6 more boys than girls in the class. The average number of pens sold by the boys was 14. Find the average number of pens sold by the girls.
| |
Girls |
Boys |
Total |
| Number |
1 u |
1 u + 6 |
24 |
| Value |
? |
14 |
20 |
| Total value |
270 |
210 |
480 |
Total number of pens sold
= 24 x 20
= 480
Number of girls = 1 u
Number of boys = 1 u + 6
1 u + 1 u + 6 = 24
2 u + 6 = 24
2 u = 24 - 6
2 u = 18
1 u = 18 ÷ 2 = 9
Number of boys in class
= 1 u + 6
= 9 + 6
= 15
Number of pens sold by boys
= 15 x 14
= 210
Number of pens sold by girls
= 480 - 210
= 270
Average number of pens sold by girls
= 270 ÷ 9
= 30
Answer(s): 30
