The price of milk was first increased by 10% and then decreased by 20%. What is the net percentage change in final price of milk?

The population of a city is 50,000 at present. It increases at the rate of 10% per annum. What was its population 4 years ago from present?

a:b = 3:7 and b:c = 9:5. What is a:b:c?

An amount becomes 7 times in 15 years. In how many years will the same amount become 10 times? The rate of interest remains the same for both cases.

An amount becomes 4 times in 6 years. In how many years will it become 64 times if the rate of interest remains unchanged?

Amit gave his friend Rs. 11000. This loan was to be repaid in 3 yearly installments with a rate of interest of 20% compounded annually. How much would be the value of each installment?

A boy increases his speed to 9/5 times of his original speed. By this he reaches his school 30 minutes before the usual time. How much time does he takes usually?

Pratik travels 96 km at a speed of 16 km/hr using a bike, 124 km at 31 km/h by car and another 105 km at 7 km/h in horse cart. Then, find his average speed for the entire distance travelled?

The average age of 10 students and their teacher is 15 years. The average age of the first seven students is 15 yr and that of the last three is 11 yr. What is the teacher's age?

P and Q together can do a work in 18 days. P alone can do the same work in 27 days. In how many days can Q alone do the same work?