SAT Subject Test Mathematics Level 1

To get the new average, add 77 and divide by 5:

The answer is (E).

USE THE SUM

The key to  many    averages    questions   is  to  use this    variant of  the

Average formula: Sum    of  the terms   =   (Average)   ×   (Number of  terms)

DISTANCE, RATE, AND TIME

Yet another classic situation with a standard approach is the distance-rate-
and-time question. Example 8 is an interesting variation.

Example 8

Martha  drives  half    the distance    from    A   to  B   at  40  miles   per hour    and the

other   half    the distance    at  60  miles   per hour.   What    is  her average rate    of

speed,  in  miles   per hour,   for the entire  trip?

1.

(A) 48

(B) 49

(C) 50

(D) 51