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? 

Ifennaoffor

3 years ago

how did you get 12×5 divided by 3
is it not meant to be
12boys=

Nickcollins12

3 years ago

I used this method:
Let boys be b and girls g;
4b and 10g in 5hrs;
b=5/4 of g;
5/4 of g x 4 =5g;
5g and 10g in 5hrs;
15g = k/5hrs;
k =75;
If 3hrs:
? = 75/3hrs = 25g

b = 5/4 of g;
? = 25g;
? x 5/4 of g = 25;
? = 25 / (5/4);
? = 25 x (4/5);
? = 20 boys.