The mean weight of 12 packages a retailer needs to ship on Monday is 10 ounces. The retailer pays 50 cents per ounce on shipping, plus one dollar per package for insurance on five of the packages. If two additional packages must be shipped on Monday, the percent increase on the retailer’s shipping cost for that day is less than 20% if neither package is insured and greater than 20% if one package is insured. What is the combined weight of the two additional packages, in ounces ?

A) 23
B) 24
C) 25
D) 26
E) 27


OA C

Source: Princeton Review