Verbal Reasoning - Mental Ability Questions

In this question, some equations are solved on the basis of a certain system. On the same basis find out the correct answer from amongst the four alternatives for the unsolved equation.

462 = 551
398 = 487
856 = ?

In the following question, select the related letters from the given alternatives.
KLMN : IJKL : : TUVW : ?

Find the next in this series:
YC3, XF6, WI9, ........

If 6#30=5; 8#24=3; 7#28=4; then what is the value of 8#40=?

Rajiv is the brother of Arun. Sonia is the sister of Sunil. Arun is the son of Sonia. How is Rajiv related to Sunil?

If 8 θ 12 δ 6 = 60 and 13 θ 15 δ 11 = 74, then 18 θ 21 δ 15 = ?

Which set of letters when sequentially placed at the gaps in the given letter series shall complete it?

MN_NOM_OPM_OP_

Each of the following questions hasfour statements. Three are logically correct. Some of which may look factually absurd. Ignore this absurdity and look to the logical corrections. Choose the statement which is wrong or doubtful: