A person borrows some money for 8 years at a rate of simple interest. If the ratio of principal and total interest is 5 : 8, then what is the rate ( inpercentage) of interest?
A boat cover row 12 km upstream in 4 hours and can cover the same distance downstream in 3 hours. What is the speed (in km/hr) of the boat in still water?
The ratio of the number of boys and girls in a school is 3:2. If 20% of the boys and 25% of the girls are scholarship holders, the percentage of the school students who are not scholarship holders is