Mean

First find the sum of the given data.

(sum) = 60 + 70 + 80 + 90 + 100

60 + 100 = 160
70 + 90 = 160

160 + 160 = 320

320 + 80 = 400

There are 5 values.

So n = 5.

(sum) = 400
n = 5

Then (mean) = 400/5.

400/5 = 80

So 80 is the mean of the given data.

To find the mean from a frequency table,
first find (value)⋅(frequency) for each value.

Draw a 3 column table like this.

Name the titles
Score, Frequency, and (Score)⋅(Frequency).

Fill in the (Score)⋅(Frequency) column.

Multiply score and frequency.

0⋅1 = 0
1⋅1 = 1
2⋅4 = 8
3⋅7 = 21
4⋅5 = 20
5⋅2 = 10

Add the numbers in (Score)⋅(Frequency) column.
This is the sum of the data.

So (sum) = 1 + 8 + 21 + 20 + 10.

1 + 8 = 9
20 + 10 = 30

9 + 21 = 30

30 + 30 = 60

So (sum) = 60.

Next, to find the number of the data n,
add the frequencies.

n = 1 + 1 + 4 + 7 + 5 + 2

1 + 1 = 2
4 + 7 = 11
5 + 2 = 7

2 + 11 = 13

13 + 7 = 20

So n = 20.

(sum) = 60
n = 20

So (mean) = 60/20.

60/20 = 3

So 3 is the mean of the given data.