Question

In a nursery class of 18 pupils, the average is 4 title=" \frac{1}{2} " alt=" \frac{1}{2} " align="absmiddle" class="latex-formula">
years. What is the sum of the ages of pupils?​

Answer 1

Answer:

The sum of ages of all 18 pupils in the class = 81

Step-by-step explanation:

Total number of pupil in the class =  18

Average of years in the class = $4\frac{1}{2}$

Now, $4\frac{1}{2} = 4 + \frac{1}{2} = 4 + 0.5 = 4.5$

⇒Average of sum of ages  in the class = 4.05

Let us assume the sum of ages of all students in the class = m

By the formula for AVERAGE:

$\textrm{Average of n obseravtions} = \frac{\textrm{Sum of n observations}}{\textrm{n}}$

$\implies 4.5 = \frac{m}{18}$

or, m =  18 x 4.5 = 81

Hence, the sum of ages of all 18 pupils in the class = 81

Answer 2

Answer:

81

Step-by-step explanation:

Average = 4.5 years

Total = 18

Sum = 4.5 × 18 = 81