In a G.P. the ratio of the sum of first 3 terms is to that of first 6 terms is 125 : 152. Find the common ratio.

A manufacturer reckons that the value of a machine which costs him ₹ 31,250 depreciates each year by 20%. Find its value after 2 years.

Find the sum of n terms of series whose mth term is 2^m + 2m