In a class, 9 girls jumped an average of 1.23 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.32 m in the same test. The total average of the whole class was 1.29 m. How many boys were there?
| |
Girls |
Boys |
Children |
| Number |
9 |
1 u |
1 u + 9 |
| Value |
1.23 |
1.32 |
1.29 |
| Total Value |
11.07 |
1.32 u |
1.29 u + 11.61 |
Total number of boys = 1 u
Total number of children = 1 u + 9
Total length that the girls jumped
= 9 x 1.23
= 11.07 m
Total length that the boys jumped
= 1 u x 1.32
= 1.32 u
Total length that the children jumped
= 1.29(1 u + 9)
= 1.29 u + 11.61
11.07 + 1.32 u = 1.29 u + 11.61
1.32 u - 1.29 u = 11.61 - 11.07
0.03 u = 0.54
1 u = 0.54 ÷ 0.03 = 18
Number of boys
= 1 u
= 18
Answer(s): 18
