Question

The data to represent average test scores for a class of 24 students includes an outlier value of 89. If the mean, including the outlier of 89, equals 77, which statement is always true about the new data when the outlier is removed?

The mean would increase.

The mean would decrease.

The median would increase.

The median would decrease.

Answer 1

• B. The mean would decrease.

Explanation:

Given:

• Number of students is 24
• The mean is 77
• The outlier is 89

The sum of 24 scores:

• 77*24 = 1848

If we remove the outlier, then the sum becomes:

• 1848 - 89 = 1759

And we have 23 scores, find the mean:

• 1759 / 23 = 76.48 (rounded)

Since 76.48 < 77, the mean has decreased.

We can't see the median hence we can't state it will increase or decrease.

Correct choice is B