DRDO Multi tasking staff Model paper 2

The average revenues of 7 consecutive years of a company is Rs. 79 lakhs.
So, the total revenues of 7 consecutive years of a company = Rs. 79 × 7 lakhs = Rs. 553 lakhs.
The average of first 4 years is Rs. 74 lakhs.
So, the total of first 4 years = Rs. 74 × 4 lakhs = Rs. 296 lakhs.
The average of last 4 years is Rs 86 lakhs.
The total of last 4 years = Rs. 86 × 4 lakhs = Rs. 344 lakhs.
Then, the total revenues of last three years = Rs. 553 – 296 lakhs = Rs. 257 lakhs.
∴ The revenue for the 4th year = Rs. 344 – 257 lakhs = Rs. 87 lakhs