Two tetrahedral dice are thrown; one is red and the other is blue . The number on which each lands is noted, the faces being marked 1,2,3,4. Find the probability that the sum of the numbers on which the dice lands is 6 given that the red die lands on an odd number.

Answer 1

if red is 1, blue has to be 5, can't happen
if red is 3 blue has to be 3
So only one case

prob (of stated event) = 1/4