Correct Answer: Rs. 77.5 lakhs

Solution : Total amount invested in raw materials in given years(Rs. in lakhs)
= 120 + 225 + 375 + 330 + 525 + 420
= 1995
Number of given years = 6
Average of total investment = $\frac{\text{Total amount invested}}{\text{Total years}}$
= $\frac{1995}{6}$
= Rs. 332.5 lakhs
Total value of sales of finished goods in given years(Rs. in lakhs)
= 200 + 300 + 500 + 400 + 600 + 460
= 2460
Number of given years = 6
Average value of sales = $\frac{\text{Total value of sales of finished goods}}{\text{Total years}}$
= $\frac{2460}{6}$
= Rs. 410 lakhs
Difference = Average value of sales – Average of total investment
= 410 – 332.5 = Rs. 77.5 lakhs
Hence, the correct answer is Rs. 77.5 lakhs.