Relative Frequency

The number of times an event occurs is called a frequency. To calculate the relative frequency we need to

  • Frequency count for the total population
  • Frequency count for a subgroup of the population

We can find relative frequency in the following way if we know the above two frequencies

Relative Frequency = Subgroup Count / Total Count

So, the relative frequency is a proportion or percentage which is equal to 0.5 or 50 percent.

How to Calculate Relative Frequency

Let’s understand Relative Frequency formula with the help of example

Let’s look at the table below to see how the weights of the people are distributed.

Weight

Frequency

Relative Frequency

45 – 50

1

1 / 40 x 100 = 0.025

50 – 55

1

1 / 40 x 100 = 0.025

55 – 60

3

3 / 40 x 100 = 0.075

60 -65

6

6 / 40 x 100 = 0.15

65 – 70

8

8 / 40 x 100 = 0.2

70 – 80

11

11 / 40 x 100 = 0.275

80 -90

3

3 / 40 x 100 = 0.075

90 – 100

7

1 / 40 x 100 = 0.025

Step 1 : To convert the frequencies into relative frequencies, we need to do the following steps.

Step 2: Divide the given frequency bt the total N i.e 40 in the above case(Total sum of all frequencies).

Step 3 : Divide the frequency by total number Let’s see how : 1/ 40 = 0.25.

Examples of Relative Frequency

Let us solve few more examples to understand the concepts better.

This is a frequency table to see how many students have got marks between given intervals in Maths.

Marks

Frequency

Relative Frequency

45 – 50

3

3 / 40 x 100 = 0.075

50 – 55

1

1 / 40 x 100 = 0.025

55 – 60

1

1 / 40 x 100 = 0.075

60 -65

6

6 / 40 x 100 = 0.15

65 – 70

8

8 / 40 x 100 = 0.2

70 – 80

3

3 / 40 x 100 = 0.275

80 -90

11

11 / 40 x 100 = 0.075

90 – 100

7

1 / 40 x 100 = 0.025

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Practise This Question

If I < x < I +1, Find [-x], where I is an integr