A random sample of 20 people is classified in the following table according to their ages:
What is the mean age of this group of people?

• A

  $41.0$
• Correct answer
  B

  $41.5$
• C

  $42.0$
• D

  $42.5$

Solution

$\Rightarrow$ Mean age $=\frac{\Sigma x_i f_i}{\Sigma f_i}=\frac{836}{20}=41.5$

Hence, the correct answer is option: 'B'.