Machine A and B

[vittalgmat]

Nice one.

Machine A and Machine B are each used to manufacture 660 sprockets. It takes machine A 10 hours longer to produce 660 sprockets than machine B. Machine B produces 10 percent more sprockets per hour than machine A. How many sprockets per hour does machine A produce?

(A) 6
(B) 6.6
(C) 60
(D) 100
(E) 110

OA is A

[ace_gre]

Let the number of hours taken by B to produce 660 sprockets be x. Then A will take (x+10) hours.
Also y be the number of sprockets A produces in 1 hr. Then B will produce 1.1y in 1 hr.

y(x+10)=x(1.1y)
xy+10y=1.1xy
10y=0.1xy
x=10/0.1=100

A will produce 660 sprockets in x+10 hours==>660 in 110 hrs.
Therefore in 1 hr A produces 660/110=6 sprockets. Answer is A.