Whenever the word average is seen in a word problem on the SAT, it is important to write down the number of separate equations that will need to be solved. Averaging questions can be tricky by nature, so it is important to read them carefully and make sure the question is understood correctly.
TIP: Whatever information is given for a question, it is important to read beyond that and know exactly what the test makers are looking for as the correct answer. It may take a little more time, but when dealing with word problems containing averages, it is important to make sure that the entire question is understood correctly.
Weighted Averages
Simply put, weighted averages are those where one or more groups contribute to the outcome more than others.
Tom goes to work at an average speed of 60 mph. Assuming he takes the same road and does not stop, if he averages 40 mph on the way home, what is his average speed for the entire trip in miles per hour format?
(A) 40
(B) 48
(C) 50
(D) 52
(E) 55
The trick is to find the total number of miles driven as well as the total number of hours that it took. Once this information is known, it is simply a matter of averaging the numbers to get 48 mph for the trip.
