The average height of a group of boys was 143 cm. After 8 girls with a total of 1248 cm joined the group, the average height of all the students increased to 147 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Students |
Number |
1 u |
8 |
1 u + 8 |
Value |
143 |
? |
147 |
Total value |
143 u |
1248 |
147 u + 1176 |
(a)
Average height of girls
= 1248 ÷ 8
= 156 cm
(b)
Total height of students
= 147(1 u + 8)
= 147 u + 1176
Total height of boys and girls = 143 u + 1248
147 u + 1176 = 143 u + 1248
147 u - 143 u = 1248 - 1176
4 u = 72
1 u = 72 ÷ 4 = 18
Number of boys = 18
Answer(s): (a) 156 cm; (b) 18