Basic Probability Exercise

1. Ten disks are numbered from 1 to 10 and placed in a bag. If disks are randomly drawn from the bag, what is the probability that:

a. The number on the disk is even?
b. The number of the disk is a multiple of 3?
c. The number on the disk is an odd number and a multiple of 5?
d. The number on the disk is an even number or a multiple of 5?

2. A bag contains 6 white balls and 4 red balls. A student takes a ball from the bag.
What is the probability that the ball is:

a. White?
b. Red?
c. Green?

3. A bag contains 40 marbles, 25 blue ones, 10 green ones and 5 red ones. What is the probability of not picking out a red marble?

4. If a letter is taken at random from the word STATISTICS what is the probability that:

a. it is a vowel?
b. it is not a vowel?
c. it is a T?

5. On throwing a six-sided fair die, what is the probability of throwing:

a. A number less than 5?
b. A number more than 6?
c. A prime number?

6. If a number is chosen at random from the numbers from 1 to 40 inclusive, what is the probability that a prime number will be chosen?

7. Two dice are thrown. what is the probability that the total will be:

a. Odd?
b. 8?
c. Less than 7

8. In a car park there are 200 vehicles. 150 are cars, 30 are lorries and 20 are buses. If they are all equally likely to leave, what is the probability that:

a. A bus will be the first to leave?
b. A car will not be last to leave?