What is the principal amount? Statement I: The Simple Interest obtained on the principal after 3 years at 10% rate of interest is Rs 580 less than the compound interest obtained on the same principal after 3 years at 10% per annum. Statement II : The sum becomes double in 20 years at 8% per annum rate of simple interest. Statement III: The compound interest obtained on the principal amount is Rs 5580 after 3 years at the rate of 10% compounded annually.