Question

A random sample of 24 people is classified in the following table according to their ages:

Age	Frequency
10 – 20	4
20 – 30	6
30 – 40	8
40 – 50	2
50 - 60	4

What is the mean age of this group of people?

1. 25
2. 33.3
3. 16.67
4. 54.54

Answer 1

Correct Answer - Option 2 : 33.3

Concept:

• \({\rm{Mean}} = \frac{{\sum {\rm{xf}}}}{{\sum {\rm{f}}}}\)

Calculation:

Age	Frequency (f)	x	xf
10 – 20	4	15	60
20 – 30	6	25	150
30 – 40	8	35	280
40 – 50	2	45	90
50 - 60	4	55	220
	\(\sum {\rm{f}} = 24\)		\(\sum {\rm{xf}} = 800\)

 

We know that, \({\rm{Mean}} = \frac{{\sum {\rm{xf}}}}{{\sum {\rm{f}}}}\)

\(\therefore {\rm{Mean}} = \frac{{800}}{{24}} = 33.3\)