Question: A farm used two harvesting machines, H and K, to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate, harvested 40 acres of wheat in 8 hours. Then harvesting machine K was brought in, and harvesting machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 6 hours. Harvesting machine K harvested how many acres of wheat per hour?
Options:
(A) 4
(B) 8
(C) 12
(D) 13
(E) 15 Random thoughts:
Rate of H = 6 acres/hr
Remaining land to be harvested = 100 - 40 = 60
Rate of H and K = 60/6 = 10 acres/hr
Rate of K = 10 - 6 = 4 The final answer: (A).