Manish's average earning per month in the first three months of a year was ₹8784. In April, his earning was 25% more than the average earning in the first three months. If his average earning per month for the whole year is ₹99085, then what will be Manish's average earning (in ₹) per month from May to December?

Correct option is D

Given:
Manish's average earning per month in the first three months (January, February, March) = ₹8784

In April, his earning was 25% more than the average earning in the first three months.

His average earning per month for the whole year (12 months) is ₹99085

Formula Used:
Average​$$=\frac{\text{(Sum of numbers)}}{\text{(Total number)}}$$​

Total Sum = Average × Number of Items
​$$\text{Percentage Increase} = \text{Original Value} \times \left(1 + \frac{\text{Percentage}}{100}\right)$$​​
Solution:
The average earning for the first three months is ₹8784. 

​​Total for first 3 months = $$8784 \times 3$$​ = ₹26352

In April, Manish earned 25% more than the average earning of the first three months;

Earnings in April = $$8784 \times 1.25$$​ = ₹10980

​​Add the earnings for the first three months and April:

Earnings in April = $$8784 \times 1.25$$​ = ₹10980 

​The average earning for the whole year is ₹99085:

Total for 12 months = 99085 \times 12 = ₹1189020

Total from May to December = 1189020 - 37332 = ₹1151688  

Average from May to December = $$\frac{1151688}{8}$$ = ₹ 143961 ​

​Option (D) is right.