The radius of a right circular cone is 3.5 cm and slant height is 0.21 m, then what is its lateral surface area? (Use π = \( \frac{22}{7} \))
Amit invests a sum of โน5,400 and Gopal invests a sum of โน9,400 at the same rate of simple interest per annum. If, at the end of 5 years, Gopal gets โน600 more interest than Amit, then find the rate of interest per annum (in percentage).