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?

In a string of 20 beads, the average weight of the first 14 beads is 25 grams and that of the last 6 beads is 8 grams. What is the average weight of all the beads?

Choose the correct alternative.
Fire : Ashes :: Explosion : ? 

cccbb_aa_cc_bbbaa_c 

Direction: In the following, select the related word from the given alternatives.
Heat : Convection :: Space : ?

Find the odd word from the following:

The sum of the present ages of two cousins is 46 years. Eight year ago, the elder one was twice as old a the younger one. What is the present age of the elder cousin?