Question

The following data is for class of 5 people and their weights:
24, 26, 25, 30, 35
What happens to the average when the boy who weighs 24 kg leaves the class?

• A. It decreases by 24
• B. It increases by 1
• C. It decreases by 6
• D. It increases by 4.8

Answer 1

The correct option is B It increases by 1

We know,

$Average=\frac{Sumofallobservations}{Totalnumberofobservations}$

$Average=\frac{24+26+25+30+35}{5}=\frac{140}{5}=28$

When the boy whose wight is 24 leaves the class,
The new sum = 140 - 24 = 116
The total number of observations = 5 - 1 = 4

$\therefore$
$NewAverage=\frac{Sumofallobservations}{Totalnumberofobservations}$

$\Rightarrow$ $NewAverage=\frac{116}{4}=29$

Therefore, the average increases by 1.