<PRE><B>Question 773457</B>
1,2,3,4

The  sample space  is the set of all possible outcomes 


S={1234, 1243, 1324, 1342, 1423, 1432, 2134, 2143, 2314, 2341, 2413, 2431, 3124
 3142, 3214, 3241, 3412, 3421, 4123, 4132, 4213, 4231, 4312,4321,}

24 numbers can be formed.

number of sample points = n(S)=24

We should get a number starting from 3. How many are there?

Number of favourable outcomes Or event of a number starting from 3
denote by set A
A={3124, 3142, 3214, 3241, 3412, 3421,}
n(A)=6

probability of the number starting from 3 =( number of favorable outcomes/number of possible outcomes)

n(P) = n(A)/n(S)

=6/24

=1/4</PRE>