In a class, 9 girls jumped an average of 1.32 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.39 m in the same test. The total average of the whole class was 1.36 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
9 |
1 u |
1 u + 9 |
Value |
1.32 |
1.39 |
1.36 |
Total Value |
11.88 |
1.39 u |
1.36 u + 12.24 |
Total number of boys = 1 u
Total number of children = 1 u + 9
Total length that the girls jumped
= 9 x 1.32
= 11.88 m
Total length that the boys jumped
= 1 u x 1.39
= 1.39 u
Total length that the children jumped
= 1.36(1 u + 9)
= 1.36 u + 12.24
11.88 + 1.39 u = 1.36 u + 12.24
1.39 u - 1.36 u = 12.24 - 11.88
0.03 u = 0.36
1 u = 0.36 ÷ 0.03 = 12
Number of boys
= 1 u
= 12
Answer(s): 12