ClassFrequencyCumulative frequency65−854485−10559105−1251322125−1452042145−1651456165−185763185−205467
Here, N2=672=33.5 which lies in the interval 125-145.
Hence, upper limit of median calss is 145.
Here, we see that the highest frequency is 20 which lies in 125-145. Hence, the lower limit of modal class is 125.
∴ Required difference =Upper limit of median class-Lower limit of modal class =145-125=20