IXL - Mean absolute deviation (Algebra 1 practice)

Stefan checked the available memory on 5 computers in the computer lab. The amounts were:

3 GB

7 GB

3 GB

9 GB

7 GB

What was the mean absolute deviation of the amount of memory available?

If the answer is a decimal, round it to the nearest tenth.

mean absolute deviation (MAD): GB

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Learn with an example

question

Mr. Alexander kept track of the number of hours his 5 students spent doing volunteer work. His records showed:

3 hours

1 hour

8 hours

4 hours

9 hours

What was the mean absolute deviation of the numbers of hours spent doing volunteer work?

If the answer is a decimal, round it to the nearest tenth.

mean absolute deviation (MAD): hours

key idea

The mean absolute deviation (MAD) is a measure of how much a data set varies.

solution

Step
1:
Compute
the
mean,
μ
.

First add all of the numbers in the data set together. Then divide by the total number of values in the data set.

3 + 1 + 8 + 4 + 9

The
mean,
μ
,
is
5.

Step 2: Compute the mean absolute deviation, MAD.

Take each number in the data set, subtract the mean, and take the absolute value. Then take the sum of the absolute values.

|3 − 5| + |1 − 5| + ... + |9 − 5| = 14

Now compute the mean absolute deviation by dividing the sum above by the total number of values in the data set.

MAD

2.8

The mean absolute deviation of the numbers of hours spent doing volunteer work was 2.8.

Looking for more? Try these:

Lesson: Mean absolute deviation

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HH.1Calculate mean, median, mode, and range

Lesson: Mean absolute deviation

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