In a container, two types of liquids P and Q are in the ratio of 3 : 7. If 10 litres mixture is drawn off from the container and filled with 6 litres of liquid Q,then the ratio of P and Q becomes 1 : 3. What was the original quantity (in litres) of mixture?
If the time increases by 7 years, then simple interest increases by Rs 8400 on a sum of Rs 6000. What is the rate (in percentage) of interest per annum?