In a class, 10 girls jumped an average of 1.52 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.61 m in the same test. The total average of the whole class was 1.56 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
10 |
1 u |
1 u + 10 |
Value |
1.52 |
1.61 |
1.56 |
Total Value |
15.2 |
1.61 u |
1.56 u + 15.6 |
Total number of boys = 1 u
Total number of children = 1 u + 10
Total length that the girls jumped
= 10 x 1.52
= 15.2 m
Total length that the boys jumped
= 1 u x 1.61
= 1.61 u
Total length that the children jumped
= 1.56(1 u + 10)
= 1.56 u + 15.6
15.2 + 1.61 u = 1.56 u + 15.6
1.61 u - 1.56 u = 15.6 - 15.2
0.05 u = 0.4
1 u = 0.4 ÷ 0.05 = 8
Number of boys
= 1 u
= 8
Answer(s): 8