Bob finishes the first half of an exam in four sixth the time it takes him to finish the second half. If the whole exam takes him an hour, how many minutes does he spend on the first half of the exam? Choose one.
A) 12
B) 24
C) 27
D) 36
E) 40
Many times, it is easiest to think of problems like this conceptually (as opposed to formulaically). Conceptually, if the first half of the exam takes 4/6's the time of the second half (6/6's), we can see that the hour the entire exam took to finish can be broken down into tenth's. (Another way to look at this problem is via ratio's - first half is 4:10 and the second half is 6:10). With each tenth of an hour being 6 minutes (60/10), the first half of the exam would have taken 12 minutes. Correct answer is 12.
<result>A</result>
Bob finishes the first half of an exam in four sixth the time it takes him to finish the second half. If the whole exam takes him an hour, how many minutes does he spend on the first half of the exam?