The average height of a group of boys was 166 cm. After 7 girls with a total of 1218 cm joined the group, the average height of all the children increased to 167 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Children |
Number |
1 u |
7 |
1 u + 7 |
Value |
166 |
? |
167 |
Total value |
166 u |
1218 |
167 u + 1169 |
(a)
Average height of girls
= 1218 ÷ 7
= 174 cm
(b)
Total height of children
= 167(1 u + 7)
= 167 u + 1169
Total height of boys and girls = 166 u + 1218
167 u + 1169 = 166 u + 1218
167 u - 166 u = 1218 - 1169
1 u = 49
1 u = 49 ÷ 1 = 49
Number of boys = 49
Answer(s): (a) 174 cm; (b) 49