In a class, 15 girls jumped an average of 1.47 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.75 m in the same test. The total average of the whole class was 1.55 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
15 |
1 u |
1 u + 15 |
Value |
1.47 |
1.75 |
1.55 |
Total Value |
22.05 |
1.75 u |
1.55 u + 23.25 |
Total number of boys = 1 u
Total number of children = 1 u + 15
Total length that the girls jumped
= 15 x 1.47
= 22.05 m
Total length that the boys jumped
= 1 u x 1.75
= 1.75 u
Total length that the children jumped
= 1.55(1 u + 15)
= 1.55 u + 23.25
22.05 + 1.75 u = 1.55 u + 23.25
1.75 u - 1.55 u = 23.25 - 22.05
0.2 u = 1.2
1 u = 1.2 ÷ 0.2 = 6
Number of boys
= 1 u
= 6
Answer(s): 6