If the radius of a circle is increased by 100%, by what % is the area of the circle increased?
The monthly incomes of two persons are in the ratio 4:5 and their monthly expenditures are in the ratio of 7:9. If each saves BDT 50 per month, find their monthly income.
Simple interest on a certain sum at the rate of 4.5% p.a. for 4 years and 6 years differs by BDT 216. The sum is-