The average age of 30 boys in class and a teacher is 15. If the age of the teacher is 30 year what would be the average age of boys only ?

If 9+3-3=30 and 4+2-5=13 what is 7+4-8

How many 3s are there in the following number series which are preceded by 5 and followed by 4 if

3 1 2 3 4 5 3 4 7 8 9 3 1 5 3 4 2 6 7

What is the rational number equal to 0.712712712 .................a

A candidate appearing for an examination has to secure 40% marks to pass paperI. But he secured only 40 marks and failed by 20 marks. What is the maximum mark for paper I?

One fourth percent of 180 is: