Originally Posted by
DrSteve At this stage you should do this problem by the technique of picking numbers.
Let's choose a value for d, how about d=10, so that 10 pounds of apples is 10 dollars. Thus the apples cost 1 dollar per pound. So it's 1 dollar for 6 apples, and therefore 2 dollars for 12 apples. 2 dollars is equal to 200 cents. Put a nice big circle around the number 200. That's the answer you want to get.
Now, since we chose d=10, we substitute 10 in for d in each answer choice and use our calculator. We get the following:
(A) 200
(B) approximately 166.67
(C) 50
(D) approximately 16.67
(E) .5
Since (A) is the only answer that came out to 200, the answer is choice (A).
Important Remark: The answer is not (A) because (A) came out correct. The answer is (A) because the other 4 choices did not come out correct. You must try all 5 choices before selecting your answer.