Aptitude - Probability - Discussion

@Vrushang.

In combination(1, 1) are same, in permutations order is impt ex: (1, 2),(2, 1).

Are same selection in combs we first 1 or 2, 2 or 1 is same comb. But in permutations the arrangement is imp 1, 2 it is different from 2, 1 first 1 is set in the row next second place 2 is set, first 2 is set in the row, next 1 is set in the row.

So I think you are understand.

Prime number is nothing but a number which is divided by 1 or itself. For example 5 is divided by itself or only 1. So its called a prime number. 6 is not called a prime no because of it can divide by 2, 3. I hope now clear cut.

1 is prime no or composite no?

If we can chose (1,2) and (2,1) (2,3) and (3,2).

Then why we can't chose (1,1) both time. Not only that case we also chose (1,1) as a double event space. Please reply.

We have prime numbers between 2 To 12 as 2,3,5,7,11.

There is 1 Way to get sum as 2, 2 ways to get sum 3, 4 To get 5, 6 Ways to get 7 And 2 Ways to get 11. So total of 15, therefore prob = 15/36.

Don't you think we should not count (1,2) and (2,1) as 2 it must counted as 1 only.

How we got 15 point please anyone can explain?

No detail about the Dice's aren't they Identical (0,0).

The total no of unique combinations on throw of 2 dice is 36:

i.e. {(1,1),(1,2),(2,1),(1,3),(3,1),(2,2),(1,4),(4,1),(2,3),(3,2),(1,5),(5,1),(2,4),(4,2),(3,3),(1,6),(6,1),(2,5),(5,2),(3,4),(4,3),(2,6),(6,2),(3,5),(5,3),(4,4),(3,6),(6,3),(4,5),(5,4),(4,6),(6,4),(5,5),(5,6),(6,5),(6,6)}.

Out of these pairs, how many give us a prime number sum = 15.

i.e. {(1,1),(1,2),(2,1),(1,4),(4,1),(2,3),(3,2),(1,6),(6,1),(2,5),(5,2),(3,4),(4,3),(5,6),(6,5)}.

So, probability = 15/36 = 5/12.

Why 4 kings are taken?