A school has $20$ teachers, one of them retires at the age of $60$ years and a new teacher replaces him, this change reduces the average age of the staff by $2$ years, the age of new teacher is

Observe the following table

$\begin{array}{|ccccccc|}\hline \text{ Class }& 0-20& 20-40& 40-60& 60-80& 80-100& \text{ Total }\\ \text{ Frequency }& 17& {\mathrm{f}}_1& 32& {\mathrm{f}}_2& 19& 120\\ \hline\end{array}$

If the above data has mean $50$, then missing frequencies $f_1$ and $f_2$ are respectively

The average of first five multiples of $3$ is

Consider the following distribution:

If the mean of the above distribution is $50$, what is the value of $f$?

Read the following frequency distribution for two series of observations and answer the two items that follow: Series I and Series II is the given frequency.

What is the mean of frequency distribution of Series- I?

The mean and median of  $7, 5, 5, 2, 7, 6, 5, 3, 7, 6$is-

1. $5.3$ and $5$

2. $5$ and $5.5$

3. $5$ and $6$

4. $5.3$ and $5.5$