The average height of a group of boys was 155 cm. After 6 girls with a total of 1050 cm joined the group, the average height of all the children increased to 163 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Children |
Number |
1 u |
6 |
1 u + 6 |
Value |
155 |
? |
163 |
Total value |
155 u |
1050 |
163 u + 978 |
(a)
Average height of girls
= 1050 ÷ 6
= 175 cm
(b)
Total height of children
= 163(1 u + 6)
= 163 u + 978
Total height of boys and girls = 155 u + 1050
163 u + 978 = 155 u + 1050
163 u - 155 u = 1050 - 978
8 u = 72
1 u = 72 ÷ 8 = 9
Number of boys = 9
Answer(s): (a) 175 cm; (b) 9