You have found a mutant algae that doubles in size every hour. It takes 18 hours for one algae plant to take up half of a certain lake.
How long would it take for two of these plants to take up half of the same lake?
Options:
(A) 7
(B) 17
(C) 27
(D) 37
(E) 47 Hmmm, my stream of consciousness:
At 17 hours the one plant will take up 1/4 of the lake (1/2 of 1/2). At 17 hours the two plants would be double the size of the one plant and double 1/4 is one half. So, the answer is (B).