The average height of a group of boys was 169 cm. After 6 girls with a total of 1098 cm joined the group, the average height of all the pupils increased to 171 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Pupils |
Number |
1 u |
6 |
1 u + 6 |
Value |
169 |
? |
171 |
Total value |
169 u |
1098 |
171 u + 1026 |
(a)
Average height of girls
= 1098 ÷ 6
= 183 cm
(b)
Total height of pupils
= 171(1 u + 6)
= 171 u + 1026
Total height of boys and girls = 169 u + 1098
171 u + 1026 = 169 u + 1098
171 u - 169 u = 1098 - 1026
2 u = 72
1 u = 72 ÷ 2 = 36
Number of boys = 36
Answer(s): (a) 183 cm; (b) 36