Question

The mean score on a set of 27 tests is 78. Suppose two more students take the test and score 69 and 66. What is the new mean?

Answer 1

77.3

Explanation:

Recall that the arithmetic mean is found as follows:

sum of all data

a. m. = ---------------------------

number of data

sum

The mean score of 27 test results is thus 78 = --------

27

Note that we can find the sum of all 27 of the original scores by multiplying 78 by 27: 2106.

Now we include two more scores. Instead of the original sum, 2106, we have

2106 + 69 + 66

a. mean = ---------------------------

29

which comes out to 2241/29 = 77.3

Answer 2

77.3 to the nearest tenth.

Explanation:

The total of the scores on the set of 27 tests

= 78*27 = 2106.

After 2 more had joined the total score is 2106 + 69 + 66

= 2241.

So the new mean score = 2241 / 29

= 77.3.