The average height of a group of boys was 156 cm. After 3 girls with a total of 516 cm joined the group, the average height of all the students increased to 162 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Students |
Number |
1 u |
3 |
1 u + 3 |
Value |
156 |
? |
162 |
Total value |
156 u |
516 |
162 u + 486 |
(a)
Average height of girls
= 516 ÷ 3
= 172 cm
(b)
Total height of students
= 162(1 u + 3)
= 162 u + 486
Total height of boys and girls = 156 u + 516
162 u + 486 = 156 u + 516
162 u - 156 u = 516 - 486
6 u = 30
1 u = 30 ÷ 6 = 5
Number of boys = 5
Answer(s): (a) 172 cm; (b) 5