Pravin has โน1,612 with him. He divided it amongst his sons Rishi and Shan and asked them to invest it at 8% rate of interest compounded annually. It was seen that Rishi and Shan got same amount after 17 and 18 years respectively. How much (in โน) did Pravin give to Rishi?
Mukund invests a sum of โน5,400 and Sachin invests a sum of โน9,400 at the same rate of simple interest per annum. If, at the end of 4 years, Sachin gets โน960 more interest than Mukund, then find the rate of interest per annum (in percentage).