In a class of 500 students, Fred's grade was 20 th percentile, George's grade was 40 th percentile and Harry's grade was 60 th percentile; we need to compare the number of grades between Fred's grade and George's grade with the number of grades between George's grade and Harry's grade. We know achieving xth percentile means $\(\mathrm{x} \%\)$ of the total students scored less than you.

Fred's grade was $\(20^{\text {th \)$ percentile implies $\(20 \%\)$ of total students i.e. $\(\frac{20}{100} \times 500=100\)$ students got grades less than Fred, so Fred's grade was 101 from the bottom.

Similarly as George \& Harry got $\(40^{\text {th \)$ percentile $\(\& 60^{\text {th \)$ percentile grade respectively, we get their grades as $\(\left(\frac{40}{100} \times 500\right)+1=200+1=201 \&\left(\frac{60}{100} \times 500\right)+1=300+1=301\)$ respectively.

So, we get the number of grades between Fred's grade i.e. 101 and George's grade i.e. 201 is 201 $\(-101-1=99\)$ ( $\(=\)$ column A quantity)

Next the number of grades between George's grade i.e. 201 and Harry's grade i.e. 301 is 301 -$\(201-1=99\)$.

Hence column A quantity equals column B quantity, so the answer is (C).