If is known that, if the interest is compounded continuously, the principal changes at the rate equal to the product of the rate of interest per annum, and the principal. If the interest is compounded continuously at 5% per annum, in how many years will Rs. 100 double itself? At what interest rate will Rs. 100 double itself in 10 years `((log)_e2=0. 6931)` How much will Rs. 1000 be worth at 5% interest after 10 years? `(e^(0. 5)=1. 648)dot`