Adam who is 20 years old is 4 times as old as Mary. What will be Mary’s age when Adam is twice as old as her?

Direction: Select the related word from the given alternatives.

5 : 2431 :: 8 : ?

What should be the missing term in the following number series?
61, 67, 71, 73, 79, 83, __, 97,

Pointing to the woman in the picture, Rajiv said, “Her mother has only one grandchild whose mother is my wife.” How is the woman in the picture related to Rajiv?

In alphabet series, some alphabets are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
m _ nm _ n _ an _ a _ ma_

In the following question, select the related number from the given alternatives.
243: 819 :: 163 :?

In each of the following questions, four numbers are given out of which three are like in some manner while one is different. Choose the one which is different from the rest three?

Coal : Heat : : Wax : ?