The average height of a group of girls was 133 cm. After 6 boys with a total of 894 cm joined the group, the average height of all the children increased to 141 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Children |
Number |
1 u |
6 |
1 u + 6 |
Value |
133 |
? |
141 |
Total value |
133 u |
894 |
141 u + 846 |
(a)
Average height of boys
= 894 ÷ 6
= 149 cm
(b)
Total height of children
= 141(1 u + 6)
= 141 u + 846
Total height of girls and boys = 133 u + 894
141 u + 846 = 133 u + 894
141 u - 133 u = 894 - 846
8 u = 48
1 u = 48 ÷ 8 = 6
Number of girls = 6
Answer(s): (a) 149 cm; (b) 6