Madhya Pradesh Police Exam Model Paper 7

Given:
The average of a, b, c and d = 30
The average of a, b, c and e = 40
Formula used:
Average = (Sum of observations)/(Number of observations)
Calculations:
Average of a, b, c and d = 30
$\Rightarrow \left(\mathit{a}+\mathit{b}+\mathit{c}+\mathit{d}\right)/4=30$
$\Rightarrow \left(\mathit{a}+\mathit{b}+\mathit{c}+\mathit{d}\right)=120$ ----(i)
Average of a, b, c and e = 40
$\Rightarrow \left(\mathit{a}+\mathit{b}+\mathit{c}+\mathit{e}\right)/4=40$
$\Rightarrow \left(\mathit{a}+\mathit{b}+\mathit{c}+\mathit{e}\right)=160$ ----(ii)
Subtracting equation (i) from (ii),
$\Rightarrow \mathit{e}-\mathit{d}=40$
∴ The difference between e and d is 40.