The average height of a group of girls was 158 cm. After 6 boys with a total of 996 cm joined the group, the average height of all the students increased to 161 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 |
158 |
? |
161 |
Total value |
158 u |
996 |
161 u + 966 |
(a)
Average height of boys
= 996 ÷ 6
= 166 cm
(b)
Total height of students
= 161(1 u + 6)
= 161 u + 966
Total height of girls and boys = 158 u + 996
161 u + 966 = 158 u + 996
161 u - 158 u = 996 - 966
3 u = 30
1 u = 30 ÷ 3 = 10
Number of girls = 10
Answer(s): (a) 166 cm; (b) 10