In a class, 7 girls jumped an average of 1.31 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.49 m in the same test. The total average of the whole class was 1.42 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
7 |
1 u |
1 u + 7 |
Value |
1.31 |
1.49 |
1.42 |
Total Value |
9.17 |
1.49 u |
1.42 u + 9.94 |
Total number of boys = 1 u
Total number of children = 1 u + 7
Total length that the girls jumped
= 7 x 1.31
= 9.17 m
Total length that the boys jumped
= 1 u x 1.49
= 1.49 u
Total length that the children jumped
= 1.42(1 u + 7)
= 1.42 u + 9.94
9.17 + 1.49 u = 1.42 u + 9.94
1.49 u - 1.42 u = 9.94 - 9.17
0.07 u = 0.77
1 u = 0.77 ÷ 0.07 = 11
Number of boys
= 1 u
= 11
Answer(s): 11