2012-02-21 09:00:08

The distance in miles from Boston to five other cities is 44, 76, 52, 71, and 54. If a kilometer is approximately .62 miles, how many of the five cities are more than 85 kilometers away from Boston?
A) 1
B) 2
C) 3
D) 4
E) 5


The correct answer is C

Explanation:  We are converting miles to kilometers and know only that a kilometer is .62 miles.

If we were converting kilometers to miles, it would be as simple as taking the number of kilometers and multiplying it by .62, but, instead, we're moving from miles to kilometers, meaning we need to do the opposite of that (in an equation, this would be .62k = m, meaning m/.62 = k). Hence, we will take the number of miles and divide it by .62 to find the number of kilometers. Start with the middle distance, since any distance greater or less than that can be eliminated depending on the outcome of the middle value. 54 miles is the middle distance, so divide 54 by .62, which is just over 87 miles. Thus, that city is more than 85 km away from Boston, as are the two cities that are 71 and 76 miles away. You may as well check 52 to make sure it doesn't work. 52/.62 = .84, so it doesn't work, meaning our answer is C: 3 cities.