The average height of a group of boys was 117 cm. After 4 girls with a total of 496 cm joined the group, the average height of all the pupils increased to 118 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 |
117 |
? |
118 |
Total value |
117 u |
496 |
118 u + 472 |
(a)
Average height of girls
= 496 ÷ 4
= 124 cm
(b)
Total height of pupils
= 118(1 u + 4)
= 118 u + 472
Total height of boys and girls = 117 u + 496
118 u + 472 = 117 u + 496
118 u - 117 u = 496 - 472
1 u = 24
1 u = 24 ÷ 1 = 24
Number of boys = 24
Answer(s): (a) 124 cm; (b) 24