Quantitative Aptitude - Arithmetic Ability Questions

In the following question, four number pairs are given. The number on left side of (–) is related to the number of the right side of (–) with some Logic/Rule/Relation. Three are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives.

If √5 = 2.236, then √5/2 is

A square park having a side 22 m has two roads each 2 m wide running in the middle of it and parallel to its length and breadth. What will be the cost of gravelling the path at the rate of Rs.100/sq.m?

What is the digit in unit's place of the product 51 x 52 x 53 ...... 59?

Kaushik bought a toy for Rs. 160 and sold it for Rs. 180. The rate of profit was ___%.

Puneet lent out Rs 30000 in two parts, one at 5% and the other at 9% interest. The yearly average interest comes out to be 6%. What are the amounts (inRs) that are lent at 5% and 9% respectively?

If the number x3451 is divisible by 3, where x is a digit, what can be the sum of all such values of x?

Average marks obtained by 19 boys of a college is 56. If the highest marks and lowest marks obtained are removed, then the average reduces by 2. What is the average of the highest and lowest marks obtained?