A bad muffin eats raisins. Every Monday, he eats 1 raisin, every Tuesday, he eats 4 raisins, every Wednesday he eats 9 raisins, every Thursday he eats 16 raisins, ... and every Sunday he eats 49 raisins. What is the minimum number of raisins he eats in a month?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
To minimize the number of raisins, first minimize the number of days. The best month would thus be February not on a leap year, for 2 8 days or 4 weeks.
Also, the day the bad muffin starts on will be the day he eats on the most, so he should start on Monday. Thus each week he will eat 1 + 4 + 9 + ⋯ + 4 9 = 6 ( 7 ) ( 8 ) ( 1 5 ) = 1 4 0 raisins; since, there are 4 weeks, he eats 4 ⋅ 1 4 0 = 5 6 0 raisins as the minimum.