In a class, 15 girls jumped an average of 1.39 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.67 m in the same test. The total average of the whole class was 1.53 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
15 |
1 u |
1 u + 15 |
Value |
1.39 |
1.67 |
1.53 |
Total Value |
20.85 |
1.67 u |
1.53 u + 22.95 |
Total number of boys = 1 u
Total number of children = 1 u + 15
Total length that the girls jumped
= 15 x 1.39
= 20.85 m
Total length that the boys jumped
= 1 u x 1.67
= 1.67 u
Total length that the children jumped
= 1.53(1 u + 15)
= 1.53 u + 22.95
20.85 + 1.67 u = 1.53 u + 22.95
1.67 u - 1.53 u = 22.95 - 20.85
0.14 u = 2.1
1 u = 2.1 ÷ 0.14 = 15
Number of boys
= 1 u
= 15
Answer(s): 15