The perfect squares that end in 6 are:
These are the first five perfect squares ending in 6. Now, calculate their average:
Average = $\frac{16 + 36 + 196 + 256 + 576}{5}$Average = $\frac{1080}{5}$
Thus, the average is 216.
Therefore, the correct answer is (c) 216
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?