WEEK 7 QUESTIONS ON PROBABILITY

If the probability that an event will occur is p and the probability that it will not occur is q, which of the following is true?

• p + q = 0

• p + q = 1

• q – p = 0

• p – q = 1

The probabilities of a boy passing English and mathematics tests are x and y respectively. Find the probability of the boy failing both tests.

• 1 - (x- y) - xy.

• 1 - (x + y) + xy.

• 1 - (x+ y) - xy.

• 1 - (x- y) + xy.

Two girls are sitting on a dinning table with many boys. A person is picked randomly from the table. How many people are on the dinning table, if the probability of either of the girls being picked is 0.025?

• 80

• 100

• 70

• 120

• A

• B

• C

• D

Three coins are tossed. Find the probability that two land on heads.

• 1/2

• 1/8

• 1/6

• 3/8

A month is randomly chosen. What is the probability that the month chosen has less than 31 days?

• 1/2

• 7/12

• 3/4

• 5/12

What is the probability of drawing a 9 or diamond from a standard deck of cards?

• 4/13

• 13/52

• 1/52

• 1/13

Credit cards place a three-digit security code on the back of cards. What is the probability that a code starts with the number 7?

• 1/10

• 1/100

• 1/1000

• 1/10000

Two dice are rolled. What is the probability of not getting doubles?

• 1/6

• 5/6

• 2/3

• 1/3

A dice is rolled, then a coin is tossed. What is the probability of getting a 5 then tails?

• 1/2

• 1/6

• 1/12

• 1/4