20 : 30 : : ? : 72 

In the following question, select the number which can be placed at the sign of question mark(?) from the given alternatives.

If 8th of April falls on Mon day. what would be the 30th day of that month? 

Pointing to a man in a photograph a woman says. He is the father-in-law of the wife of only paternal grandson of my own father-in-law. How is woman related to man? 

Stethoscope: Heartbeat:: ? : Temperature 

Spider: Insect :: Crocodile : ? 

Select the set in which the numbers are related in the same way as are the numbers of the following sets. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E. g. 13 – Operations on 13 such as adding / subtracting / multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

(8, 1, 46)
(9, 4, 22)

Find the next number in the given series.

3, 13, 31, ? , 91