Question

In a mathematics class, half of the students scored 89 on an achievement test. With the exception of a few students who scored 48, the remaining students scored 79. Which of the following statements is true about the distribution of scores?

A. The mean is less than the median.
B. The mean and the median are the same.
C. The mean is greater than the mode.
D. The mean is greater than the median.

Answer 1

A. The mean is less than the median.

Explanation:

Say that half the students answered 79, and the rest 89.

We'd have a distribution something like this:

79 79 79 89 89 89

The median is in the smack middle. Since we have an even number of scores, the median would be the number between the 2 middle numbers. Here, that's 79 and 89. Thus, the median is 84.

The mean is the "average" of all values. Since we have an equal number of 79s to 89s, the mean would also be in the middle of those values (balancing an equal number on both sides). So, the mean would also be 84.

HOWEVER, we have an unspecified number of 48's.

The distribution looks something like

48 79 79 89 89 89

The median is still the same, smack middle between the 2 values in the middle. 84.

But the mean has changed. We have smaller values on the left. The mean is brought down by these 48 values. It doesn't matter how many, the fact that we have at least 1 will bring the mean, the average, down.

Answer 2

A. The mean is less than the median.

Explanation:

Half the students scored 89. The next highest score is 79. So the median is (79 + 89) / 2 = 84.

A few students scored 48, so the mean is slightly lower than the mean of 79 and 89.

Therefore, the mean is less than the median.