If each of the companies A and B invested Rs. 25 lakh in 2010, what was the average profit earned by the two companies?

Answer: Option D

Average profit of A and B in 2010
$$\begin{array}{rl}& =\frac{1}{2}\times \left[\left(\frac{90}{100}\times 25\text{ lakh}\right)+\left(\frac{70}{100}\times 25\text{ lakh}\right)\right]\\ & =\frac{1}{2}\times \left(\frac{45}{2}+\frac{35}{2}\right)\text{lakh}\\ & =\frac{80}{4}\text{ lakh}\\ & =\text{20 lakh}\end{array}$$