2012-04-09 09:00:09

Sandra has a collection of coins that contains only British, American, and Canadian coins. If the ratio of British to American coins is 1 to 4 and the ratio of American to Canadian coins is 2 to 1, and if Sandra has 40 British coins, how many total coins are in her collection?

(A) 130
(B) 160
(C) 200
(D) 280
(E) 480

The correct answer is D

Explanation: Always start math questions with the most specific piece of information given in the prompt. Here, the most specific piece of information is the number of British coins, so start by plugging 40 into the British to American ratio. If there are 40 British coins, and there is a 1:4 ratio between British and American coins, then there are 4 times as many American coins as British, or 4 x 40 coins, which is 160. Use this number in the American to Canadian ratio of 2:1. If 2 parts American is 160 coins, one part Canadian would be half that, or 80. So, the breakdown of coins is as follows:

British:40
American: 160
Canadian: 80

Add those up to find the total number of coins in Sandra’s collection: 40 + 160 + 80 = 280, making choice D correct.