In a class, 9 girls jumped an average of 1.21 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.35 m in the same test. The total average of the whole class was 1.29 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
9 |
1 u |
1 u + 9 |
Value |
1.21 |
1.35 |
1.29 |
Total Value |
10.89 |
1.35 u |
1.29 u + 11.61 |
Total number of boys = 1 u
Total number of children = 1 u + 9
Total length that the girls jumped
= 9 x 1.21
= 10.89 m
Total length that the boys jumped
= 1 u x 1.35
= 1.35 u
Total length that the children jumped
= 1.29(1 u + 9)
= 1.29 u + 11.61
10.89 + 1.35 u = 1.29 u + 11.61
1.35 u - 1.29 u = 11.61 - 10.89
0.06 u = 0.72
1 u = 0.72 ÷ 0.06 = 12
Number of boys
= 1 u
= 12
Answer(s): 12