Machine A produces 100 parts thrice as fast as Machine B does. Machine B produces 100 parts in 30 minutes. If each machine produces parts at a constant rate, how many parts does Machine A produce in 6 minutes?  Choose the correct choice from the following choices:
A) 20 B) 80 C) 40 D) 60 E) 50

Rationale: machine b produces 100 part in 30 minutes . machine a produces 100 parts thrice as fast as b , so machine a produces 100 parts in 30 / 3 = 10 minutes . now , machine a produces 100 parts in 10 minutes which is 100 / 10 = 10 parts / minute . 10 parts x a total of 6 minutes = 60 d
Answer: D