PSAT Math Multiple-Choice Question 635: Answer and Explanation

Question: 635

At the beginning of the year, 1 U.S. dollar can be exchanged for 0.9 euros, and 1 Canadian dollar can be exchanged for 0.7 U.S. dollars. If someone wants to convert 100 Canadian dollars to euros at these exchange rates and assuming that there are no transaction fees, how many euros would the person have after the conversion?

• A. 63
• B. 78
• C. 129
• D. 158

Correct Answer: A

Explanation:

(A) Let's use dimensional analysis, canceling out the units that we don't want and leaving the units that we do want (euros). In the dimensional analysis, let CAD mean Canadian dollars, let USD mean U.S. dollars, and let EUR mean euros:

The correct answer is choice (A).