The arithmetic mean of the following data is .

23, 17,20,19,21

A hollow copper pipe is 22 cm long and its external diameter is 28 cm. If the thickness of the pipe is 3 cm and iron weighs 8.5 g/cm³ , then the weight of the pipe is closest to:

If in a triangle, the orthocenter lies on vertex, then the triangle is 

Find co-ordinates of the midpoint of the segment joining points C (3, -5) and D ( -7,3) 

2 years, a sum was put at SI at a certain rate. If the rate was 3 % higher, it would have fetched 300 more. What will be the sum? 

The least number which when divided by 4, 6, 8 and 9 leave zero remainders in each case and when divided by 13 leaves a remainder of 7 is: 

The following table shows the number of units of product produced and sold by a company during six years.

Find the ratio of the total number of units sold in 2013 and 2015 to the number of units sold in 2015 and 2016?

The mean of the first 7 prime numbers is: