Verbal Reasoning - Mental Ability Questions

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
_ yzaa _ y _ xy _ aazy _

The first term in a sequence is 1 and the second term is 5. From the third term on each term is the average (arithmetic mean) of all preceding terms. What is the 25th term in the sequence?

Identify the diagram that best represents the relationship among the given classes.
Mammals, Dogs, Humans

If Deplete : Exhaust then Replenish : ___

Identify the diagram that best represents the relationship among the given classes.  Politician, Minister, Human

1Mithilesh said to Neha, 'Your only brother's son is my wife's brother.' How is Neha related to the wife of Mithilesh?

There are five students - P, Q, R, S and T having different heights in a class. P's height is more than only one student. Q's height is more than S and P
but not more than R. S's height is more than P. R is not the smallest. Who is having the maximum height in the class?

If P denotes ÷ , Q denotes x, R denotes + and S denotes ­ then what is the value of 18Q12P4R5S6