In a class, 9 girls jumped an average of 1.57 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.59 m in the same test. The total average of the whole class was 1.58 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
9 |
1 u |
1 u + 9 |
Value |
1.57 |
1.59 |
1.58 |
Total Value |
14.13 |
1.59 u |
1.58 u + 14.22 |
Total number of boys = 1 u
Total number of children = 1 u + 9
Total length that the girls jumped
= 9 x 1.57
= 14.13 m
Total length that the boys jumped
= 1 u x 1.59
= 1.59 u
Total length that the children jumped
= 1.58(1 u + 9)
= 1.58 u + 14.22
14.13 + 1.59 u = 1.58 u + 14.22
1.59 u - 1.58 u = 14.22 - 14.13
0.01 u = 0.09
1 u = 0.09 ÷ 0.01 = 9
Number of boys
= 1 u
= 9
Answer(s): 9