F.3 12.1 Introduction to Probability

A letter is chosen randomly from the word ‘HELLO’. Find the
       probability of choosing "L".

A letter is chosen randomly from the word ‘DIFFERENCE’. Find the

probability of choosing "E".

Six cards are marked with the numbers 2, 3, 4, 4, 7 and 8 respectively.

If a card is selected at random, find the probability that the number on

the card selected is an even number.

At midnight, there are only six customers in a restaurant. Their ages are 20, 23, 27, 39, 42 and 51. If a customer is chosen at random, find the probability  that
the age of the customer is an even number.

At midnight, there are only six customers in a restaurant. Their ages are 20, 23, 27, 39, 42 and 51. If a customer is chosen at random, find the probability that

the sum of the two digits of the age of the customer (兩位數字的總和) is greater than 5.

There are 24 eggs inside a basket and 2 of them are rotten. If one

egg is taken out at random, find the probability that it is NOT rotten.

A number is randomly selected from the 30 integers 1 to 30. What is

the probability that the number selected is a multiple of 5?

There are 15 balls in a bag, and n of them are red balls. If a ball is drawn at random  from the bag, the probability of drawing a red ball is  $\frac{1}{3}$   . Find the value of n.