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.

P + Q = 2(P-Q). If Q = 10, what is the value of P?

What will be the maturity value, if Rs. 13,500 is deposited at a simple rate of interest of 12.5% for two years?

The length of the diameter of the circle is 10 cm and length of the chord drawn in a circle is 6 cm. Find the distance (in cm) of chord from the center.

The sum of 5/8 and 8/5 is

If the standard deviation of a population is 7, what would be the population variance?

What is the sum of all prime numbers between 60 and 80?

Two ships are sailing in the sea on the two sides of a light house. The angle of elevation of the top of the light house as observed from the two ships are 30° and 45° respectively. If the light house is 100m high, the distance between the two ships is :(take √3=1.73)