A man retired from his service at the age of 60. He served for 3/5th years of his retirement age. He joined his job at the age of :

The ratio of the areas of two squares one having double its diagonal than the other is

The radius of a sphere is doubled. The percentage of increase in its surface area is

A dealer marks his goods 20% above cost price. He then allows some discount on it and makes a profit of 8%. The rate of discount is :

The price of electricity has been increased by 25%. If a person wants to keep the expenditure same, then the percentage reduction in use of electricity should be :

A sum was doubled with 12 1/2% rate of simple interest, per annum. Then time taken for that sum is: