In a class, 12 girls jumped an average of 1.24 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.38 m in the same test. The total average of the whole class was 1.31 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
12 |
1 u |
1 u + 12 |
Value |
1.24 |
1.38 |
1.31 |
Total Value |
14.88 |
1.38 u |
1.31 u + 15.72 |
Total number of boys = 1 u
Total number of children = 1 u + 12
Total length that the girls jumped
= 12 x 1.24
= 14.88 m
Total length that the boys jumped
= 1 u x 1.38
= 1.38 u
Total length that the children jumped
= 1.31(1 u + 12)
= 1.31 u + 15.72
14.88 + 1.38 u = 1.31 u + 15.72
1.38 u - 1.31 u = 15.72 - 14.88
0.07 u = 0.84
1 u = 0.84 ÷ 0.07 = 12
Number of boys
= 1 u
= 12
Answer(s): 12