Find Modal and Median Classes from Grouped Data

How many siblings do you have?

In a survey about the number of siblings of students in a Year 9 class, the data was grouped as follows:

We can use this table to find the modal and the median class.

Mode

The mode is the most common value, so we need to look at which answer has the highest frequency.

We can see that the answer of between 2-3 siblings has the highest frequency (6).

So the modal class is 2-3.

Median

The median is the middle value and we can determine in which class it lies by finding its position.

Since we have 5 + 6 + 4 + 2 = 17 students surveyed altogether, the median will be at the (17 + 1) ÷ 2 = 9th position.

There are 5 people in the 0-1 class.

Then the next 6 (i.e. the 6th to 5 + 6 = 11th) are in the 2-3 class.

So the 9th person falls into the 2-3 class.

Since we have grouped data and so don't know the exact values, we have the median class: 2-3 siblings.

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