An amount doubles itself in 5 years simple interest. What is the rate of interest per year?

In the given figure if each of the outer circles have radii ‘R’, then the radius of the inner circle will be:

Costs of two articles were in the ratio of 16: 23. The cost of first articles increases by 10% and that of second by Rs.477. Now the costs of two articles are in a ratio of 11: 20. The price of the second article (in Rs.) in the beginning was-

In a polygon, the sum of the interior angles is double the sum of the exterior angles. What is the number of sides of the polygon?

A solid metallic cylinder of base radius 3 cm. and height 5 cm. is melted to form cones, each of height 1 cm. and base radius 1 mm. The number of cones is -

A sum of money was lent at 10% per annum, compounded annually, for 2 years. If the interest was compounded half - yearly, he would have received Rs.660.75 more. Find the sum.

If the areas of circular ring having inner and outer radius 8 cm and 12 cm respectively is equal to the total surface area of cylinder of radius R₁ and height h, then h in terms of R₁ will be :

The price of an article is reduced by 25% but the daily sale of the article is increased by 30%. The net effect on the daily sale receipts is