TT-GWD5-11

A certain business produced x rakes each month form November through February and shipped x/2 rakes at the beginning of each month from March through October.  The business paid no storage costs for the rakes from November through February, but it paid storage costs of $0.10 per rake each month from March through October for the rakes that had not been shipped.  In terms of x, what was the total storage cost, in dollars, that the business paid for the rakes for the 12 months form November through October?

A.      0.40x

B.      1.20x

C.     1.40x

D.     1.60x

E.      3.20x

Answer: C

我怎么算不出答案呢？

Nov to Feb, producing 4x

Mar: 7/2 left and stored

April: 6/2 left and stored

...

Oct: 0 left

Sum=0.1*{(7/2+0)*8/2}

为啥每个月的都会不一样呢？