EASY
AS and A Level
IMPORTANT
Earn 100

The faces of a biased die are numbered 1, 2, 3, 4, 5 and 6. The random variable X is the score when the die is thrown. The probability distribution table for X is given.

x 1 2 3 4 5 6
PX=x p p p p 0.2 0.2

The die is thrown 3 times. Find the probability that the score is at least 4 on at least 1 of the 3 throws.

Important Questions on Probability Distributions

EASY
AS and A Level
IMPORTANT

A picnic basket contains five jars: one of marmalade, two of peanut butter and two of jam. A boy removes one jar at random from the basket and then his sister takes two jars, both selected at random.

Find the probability that the sister selects her jars from a basket that contains:

exactly one jar of jam

EASY
AS and A Level
IMPORTANT

A picnic basket contains five jars: one of marmalade, two of peanut butter and two of jam. A boy removes one jar at random from the basket and then his sister takes two jars, both selected at random.

Find the probability that the sister selects her jars from a basket that contains:

exactly two jars of jam.

EASY
AS and A Level
IMPORTANT

A picnic basket contains five jars: one of marmalade, two of peanut butter and two of jam. A boy removes one jar at random from the basket and then his sister takes two jars, both selected at random.

Draw up the probability distribution table for J, the number of jars of jam selected by the sister, and show that EJ=0.8.

EASY
AS and A Level
IMPORTANT

Two ordinary fair dice are rolled. The product and the sum of the two numbers obtained are calculated. The score awarded, S, is equal to the absolute (i.e. non-negative) difference between the product and the sum.
For example, if 5 and 3 are rolled, then S=5×3-5+3=7.

State the value of S when 1 and 4 are rolled.

EASY
AS and A Level
IMPORTANT

Two ordinary fair dice are rolled. The product and the sum of the two numbers obtained are calculated. The score awarded, S, is equal to the absolute (i.e. non-negative) difference between the product and the sum.
For example, if 5 and 3 are rolled, then S=5×3-5+3=7.

Draw up a table showing the probability distribution for the 14 possible values of S, and use it to calculate E(S).

EASY
AS and A Level
IMPORTANT

A fair triangular spinner has sides labelled 0,1 and 2, and another fair triangular spinner has sides labelled -1,0 and 1. The score, X, is equal to the sum of the squares of the two numbers on which the spinners come to rest.

List the five possible values of X.

EASY
AS and A Level
IMPORTANT

A fair triangular spinner has sides labelled 0,1 and 2, and another fair triangular spinner has sides labelled -1,0 and 1. The score, X, is equal to the sum of the squares of the two numbers on which the spinners come to rest.

Draw up the probability distribution table for X.

EASY
AS and A Level
IMPORTANT

A fair triangular spinner has sides labelled 0,1 and 2, and another fair triangular spinner has sides labelled -1,0 and 1. The score, X, is equal to the sum of the squares of the two numbers on which the spinners come to rest.

Given that X<4, find the probability that a score of 1 is obtained with at least one of the spinners.