In a class, 12 girls jumped an average of 1.35 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.5 m in the same test. The total average of the whole class was 1.4 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
12 |
1 u |
1 u + 12 |
Value |
1.35 |
1.5 |
1.4 |
Total Value |
16.2 |
1.5 u |
1.4 u + 16.8 |
Total number of boys = 1 u
Total number of children = 1 u + 12
Total length that the girls jumped
= 12 x 1.35
= 16.2 m
Total length that the boys jumped
= 1 u x 1.5
= 1.5 u
Total length that the children jumped
= 1.4(1 u + 12)
= 1.4 u + 16.8
16.2 + 1.5 u = 1.4 u + 16.8
1.5 u - 1.4 u = 16.8 - 16.2
0.1 u = 0.6
1 u = 0.6 ÷ 0.1 = 6
Number of boys
= 1 u
= 6
Answer(s): 6