The simple interest on a certain sum of money at the rate of 5% per annum for 8 years is Rs.1680. Rate of interest for which the same amount of interest can be received on the same sum after 5 years is -

The average age of a family of 7 members changes from 37 to 31 year due to death of the head of the family. Find the age of the head of the family.

Mr. A has opened a shop to sell milk. The fixed cost (such as rent, etc) is Rs. 8,000 per month. He purchases pure milk at Rs. 15 per litre, adds water to that milk and sells it for Rs. 20 per litre. In a month, if he sells exactly 1,000 litres of milk and gets Rs. 3,000 profit (after removing fixed cost), what is the ratio of milk to water in the milk that he has sold?

‘A’ sells an article to ‘B’ at a profit of 20% and ‘B’ sells it to ‘C’ at a profit of 25%. If ‘C’ pays Rs. 1,200, the cost price of the article originally (in Rs.) is:

Two successive discounts of 10% and 10% is equivalent to a single discount of:

A shop gives a discount of 27% on a certain brand of cloths and earns a profit of 15% on each scale.How much percentage above the cost price has the brand been marked?

Find the mean proportional between 0.16 and 0.36.

Among the three numbers, first number is 75% of second number which in turn is 125% of the third number. If the first number is 270, then what is the value of third number?

Chandan travelled equal distance with speed of 3 km/hr, 4 km/hr and 8 km/hr and takes a total time of 42.5 minutes. Find the total distance in km.

Aarti is 3 times as efficient as Bimla and Aarti can finish a work in 40 days less than the time taken by Bimla to finish the same work. In how many days can Aarti and Bimla together finish the work?