What is the compound interest (in ₹) on ₹80,000 for 3 years when the rate of interest is 5%, 8% and 10% per annum for the 3 successive years, the interest being compounded annually?
A boat covers 12 km upstream & 18 km downstream in 3 hrs, while it covers 36 km upstream & 24 km downstream in 6.5 hrs. What is the speed of the current?