The average height of a group of boys was 144 cm. After 4 girls with a total of 608 cm joined the group, the average height of all the pupils increased to 146 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Pupils |
Number |
1 u |
4 |
1 u + 4 |
Value |
144 |
? |
146 |
Total value |
144 u |
608 |
146 u + 584 |
(a)
Average height of girls
= 608 ÷ 4
= 152 cm
(b)
Total height of pupils
= 146(1 u + 4)
= 146 u + 584
Total height of boys and girls = 144 u + 608
146 u + 584 = 144 u + 608
146 u - 144 u = 608 - 584
2 u = 24
1 u = 24 ÷ 2 = 12
Number of boys = 12
Answer(s): (a) 152 cm; (b) 12