Quantitative Aptitude - Arithmetic Ability Questions

In the following question, four groups of three numbers are given. In each group the second and third number are related to the first number by a Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

Find the maximum area of a rectangle field which is surrounded by a rope of 400 m.

Find the average of all prime numbers between 20 and 50.

The simple interest on a sum for 5 years is two­fifth of the sum. The rate of interest per annum is

Find the number which is NOT a prime number.

How many prime numbers are there between the positive integers 60 and 100?

Find the volume (in cm3) of a right circular cylinder of diameter 42 cm and height 14 cm.

What is the square root of 6561?