The average height of a group of girls was 170 cm. After 3 boys with a total of 546 cm joined the group, the average height of all the students increased to 173 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Students |
Number |
1 u |
3 |
1 u + 3 |
Value |
170 |
? |
173 |
Total value |
170 u |
546 |
173 u + 519 |
(a)
Average height of boys
= 546 ÷ 3
= 182 cm
(b)
Total height of students
= 173(1 u + 3)
= 173 u + 519
Total height of girls and boys = 170 u + 546
173 u + 519 = 170 u + 546
173 u - 170 u = 546 - 519
3 u = 27
1 u = 27 ÷ 3 = 9
Number of girls = 9
Answer(s): (a) 182 cm; (b) 9