The average height of a group of boys was 140 cm. After 7 girls with a total of 1036 cm joined the group, the average height of all the students increased to 141 cm.
- What was the average height of the girls?
- How many boys were there in the group?
|
Boys |
Girls |
Students |
Number |
1 u |
7 |
1 u + 7 |
Value |
140 |
? |
141 |
Total value |
140 u |
1036 |
141 u + 987 |
(a)
Average height of girls
= 1036 ÷ 7
= 148 cm
(b)
Total height of students
= 141(1 u + 7)
= 141 u + 987
Total height of boys and girls = 140 u + 1036
141 u + 987 = 140 u + 1036
141 u - 140 u = 1036 - 987
1 u = 49
1 u = 49 ÷ 1 = 49
Number of boys = 49
Answer(s): (a) 148 cm; (b) 49