Modal Class Exercise

The masses, in grams, of 100 potatoes are shown in the table below:

Mass (m) grams Frequency

0 < m 20 1

20 < m 40 17

40 < m 60 28

60 < m 80 25

80 < m 100 19

100 < m 120 10

Calculate the mean mass of potatoes and work out the modal class and median mass.

Add another column for ?

and another row for ?

Mid mass x frequencyTotals

Mass (m) grams

Frequency Mid mass x frequency

0 < m 20 1 10

20 < m 40 17 510

40 < m 60 28 1400

60 < m 80 25 1750

80 < m 100 19 1710

100 < m 120 10 1100

Totals 100 6480

Mean

Modal class

Median

Mean is 8.641006480 Grams

How would we find out the mean?

Divide

by

Mass (m) grams

Frequency Mid mass x frequency

0 < m 20 1 10

20 < m 40 17 510

40 < m 60 28 1400

60 < m 80 25 1750

80 < m 100 19 1710

100 < m 120 10 1100

Totals 100 6480

Modal class

What does mode mean?

So which is the most or

biggest frequency?

28Which class does the 28 appear?

40 < m 60

Mass (m) grams

Frequency Mid mass x frequency

0 < m 20 1 10

20 < m 40 17 510

40 < m 60 28 1400

60 < m 80 25 1750

80 < m 100 19 1710

100 < m 120 10 1100

Totals 100 6480

Median

What does median mean?What is the middle frequency?

50Working down from the top, where would the 50th value be found?

What mass class is this in?60 < m 80

Now make the Cumulative Frequency diagram AND box plot.

Mass (m) grams

Frequency Mid mass x frequency

0 < m 20 1 10

20 < m 40 17 510

40 < m 60 28 1400

60 < m 80 25 1750

80 < m 100 19 1710

100 < m 120

10 1100

Totals 100 6480

Cumulative Frequency

10

520

1920

3670

5380

6480

Cumulative frequecy diagram

0

1000

2000

3000

4000

5000

6000

7000

0 20 40 60 80 100 120

Mass (grams)

C.

F.

Min MaxLQ M UQ