The average height of a group of girls was 149 cm. After 6 boys with a total of 942 cm joined the group, the average height of all the students increased to 151 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Students |
Number |
1 u |
6 |
1 u + 6 |
Value |
149 |
? |
151 |
Total value |
149 u |
942 |
151 u + 906 |
(a)
Average height of boys
= 942 ÷ 6
= 157 cm
(b)
Total height of students
= 151(1 u + 6)
= 151 u + 906
Total height of girls and boys = 149 u + 942
151 u + 906 = 149 u + 942
151 u - 149 u = 942 - 906
2 u = 36
1 u = 36 ÷ 2 = 18
Number of girls = 18
Answer(s): (a) 157 cm; (b) 18