The average height of a group of girls was 165 cm. After 6 boys with a total of 1122 cm joined the group, the average height of all the students increased to 177 cm.
- What was the average height of the boys?
- How many girls were there in the group?
|
Girls |
Boys |
Students |
Number |
1 u |
6 |
1 u + 6 |
Value |
165 |
? |
177 |
Total value |
165 u |
1122 |
177 u + 1062 |
(a)
Average height of boys
= 1122 ÷ 6
= 187 cm
(b)
Total height of students
= 177(1 u + 6)
= 177 u + 1062
Total height of girls and boys = 165 u + 1122
177 u + 1062 = 165 u + 1122
177 u - 165 u = 1122 - 1062
12 u = 60
1 u = 60 ÷ 12 = 5
Number of girls = 5
Answer(s): (a) 187 cm; (b) 5