A sum of money doubles itself at simple interest in 8 years. What is the annual rate of interest?
SI = P in 8 years => P = (P * R * 8) / 100 => R = 100 / 8 = 12.5%.
Which of the following statements are CORRECT about the compound interest problem?
The listed statements are correct.
Find the difference between compound interest and simple interest on Rs. 5000 for 2 years at 8% per annum.
Difference for 2 years = P * (R/100)^2 = 5000 * (8/100)^2 = 5000 * (64 / 10000) = Rs. 32.
A popuation of a town increases by 5% annually. If its present population is 80,000, what will be its population after 2 years?
$Population = 80000 * (1 + 0.05)^2 = 80000 * 1.1025 = 88,200.$
If 30% of a number is 120, what is 45% of that number?
Number = 120 / 0.30 = 400. 45% of 400 = 0.45 * 400 = 180.