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Solve the following problems. 1.1 Find the simple interest on P600D from 16 May 2010 to 9 October 2010 at 10% per annum. 2.] In how much time will S.I. on certain sum of money at 121/2% per annum be 7/, of itself? 3.) At what rate per cent annum will a sum of money double itself in 6 year? 4.) In what time will a sum of money double itself at 5 % per annum?. 5.] A certain sum amounts to P2200 in 2 years to P2800 in 4 years at simple interest. Find the sum and the rate per cent per annum