For the following questions answer them individually
Simple interest on a certain sum of money for 3 years at 8% per annum is half the compound interest on Rs 1200 for 2 years at 10% per annum. The sum placed on simple interest is
What is the length of the arc whose central angle is 30° and radius of the circle is 21 cm?
A solid copper sphere of radius 9 cm is melted and reformed into a wire of radius 1 mm. What will be the length of this wire? (Take π = 22/7)