Four boys and ten girls can cut a field first in 5 hours. If the boys work at (frac{5}{4}) the rate at which the girls work, how many boys will be needed to cut the field in 3 hours?
-
A.
180 -
B.
60 -
C.
25 -
D.
20
Correct Answer: Option D
Explanation
Let x rep. numbers of boys that can work at (frac{5}{4}) the rate at
which the 10 girls work
For 1 hrs, x boys will work for (frac{frac{1}{5} times 10}{4})
x = (frac{5}{4}) x 10
= 8 boys
8 boys will do the work of ten girls at the same rate
4 + 8 = 12 bous cut the field in 5 hrs for 3 hrs,
(frac{12 times 5}{3}) boys will be needed = 20 boys.
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