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.

Determine the value of a/b + b/a when a + b = 8 and ab = 4.

Four numbers A, B, C and D are such that their overall average is 16. The average of A and B is 9.5. The average of C and D is

3 men dig a hole in 10 days. How many days would it take for 5 men to dg the same hole?

If X and Y are the two digits of the number 347XY such that the number is completely divisible by 80, then what is the value of X + Y?

Aparna changes the marked price of an item to 50% above its C.P. What % of discount allowed in approximately to gain 10%?

If ABCD is a trapezium, AC and BD are the diagonals intersecting each other at point O. Then AC : BD is

Coefficient of x in (x + 11)(3 -­ 5x) is _____.