The average height of a group of girls was 149 cm. After 4 boys with a total of 624 cm joined the group, the average height of all the students increased to 150 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Students |
Number |
1 u |
4 |
1 u + 4 |
Value |
149 |
? |
150 |
Total value |
149 u |
624 |
150 u + 600 |
(a)
Average height of boys
= 624 ÷ 4
= 156 cm
(b)
Total height of students
= 150(1 u + 4)
= 150 u + 600
Total height of girls and boys = 149 u + 624
150 u + 600 = 149 u + 624
150 u - 149 u = 624 - 600
1 u = 24
1 u = 24 ÷ 1 = 24
Number of girls = 24
Answer(s): (a) 156 cm; (b) 24