A two digit number is selected at random. Find the number selected is an odd number.

A decimal numeral from (0,1,2,3,4,5,6,7,8,9) is selected at random. Find the chance it is a prime number.

A number is selected at random from the first 25 natural numbers. If it is a composite number, then it is divided by 5. But if it is not a composite number, it is divided by 2. Find the probability that there will be no remainder in the division.

A four digit number (numbered from 0000 to 9999) is said to be lucky if sum of its first two digits is equal to the sum of its last two digits. If a four digit number is picked up at random then the probability that it is lucky number is :-

The sum fo digits of a two-digits number is 9.If 27 is subtracted from the number then digit interchange their places. Find the number.

What is the probability that the numbers selected from the numbers 1, 2, 3, .... , 30 is a prime number ? You may assume that each of the 30 numbers is equally likely to be selected.

From the pair of linear equations in the following problems and find their solutions (if they exist) by elimination method : Seven times a given two digit number is equal to four times the number obtained by interchanging the digits and the difference of digits is 3. Find the number

Eight dice are rolled at random. Find the mean and variance of number of successes if : getting an odd number is success.

Form the pair of linear equations in the following problems, and find their solutions (if they exist) by the elimination method : The sum of the digits of a two-digit number is 9. Also, nine times this number is twice the number obtained by reversing the order of the number. Find the number.

What is the probability that a number selected from the numbers 1, 2, 3......27 is a prime number ? You may assume that each of 27 numbers is equally likely to be selected.