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.

What is the sum of the first 11 terms of an arithmetic progression if the first term is -31 and last term is 29?

If the amount received at the end of 2nd and 3rd year as Compound Interest on a certain Principal is Rs 2100, and Rs 2268 respectively, what is the rate (in %) of interest?

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.

If 9x - 6(3 - x) = 12, then the value of x is

If the 3rd and the 5th term of an arithmetic progression are 13 and 21, what is the 13th term?

If a + b = 8 and ab =15, then a3 + b3 is

If √(1 + cot2A) = x, then the value of x is