EASY
AS and A Level
IMPORTANT
Earn 100

X is a discrete random variable and X0, 1, 2, 3. Given that PX>1=0.24, P0<X<3=0.5 and P(X=0 or 2)=0.62, find P(X2X>0).

Important Questions on Probability Distributions

EASY
AS and A Level
IMPORTANT

Four students are to be selected at random from a group that consists of seven boys and x girls. The variables B and G are, respectively, the number of boys selected and the number of girls selected.

Given that PB=1=PB=2, find the value of x.

EASY
AS and A Level
IMPORTANT

Four students are to be selected at random from a group that consists of seven boys and x girls. The variables B and G are, respectively, the number of boys selected and the number of girls selected.

Given that G3, find the probability that G=4.

EASY
AS and A Level
IMPORTANT

A box contains 2 green apples and 2 red apples. Apples are taken from the box, one at a time, without replacement. When both red apples have been taken, the process stops. The random variable X is the number of apples which have been taken when the process stops.

Show that PX=3=13

EASY
AS and A Level
IMPORTANT

A box contains 2 green apples and 2 red apples. Apples are taken from the box, one at a time, without replacement. When both red apples have been taken, the process stops. The random variable X is the number of apples which have been taken when the process stops.

Draw up the probability distribution table for X. Another box contains 2 yellow peppers and 5 orange peppers. Three peppers are taken from the box without replacement.

MEDIUM
AS and A Level
IMPORTANT

A box contains 2 green apples and 2 red apples. Apples are taken from the box, one at a time, without replacement. When both red apples have been taken, the process stops. The random variable X is the number of apples which have been taken when the process stops.

Given that at least 2 of the peppers taken from the box are orange, find the probability that all 3 peppers are orange.

EASY
AS and A Level
IMPORTANT

In a particular discrete probability distribution the random variable X takes the value 120r with probability r45, where r takes all integer values from 1 to 9 inclusive.
Show that PX=40=115.

EASY
AS and A Level
IMPORTANT

In a particular discrete probability distribution the random variable X takes the value 120r with probability r45, where r takes all integer values from 1 to 9 inclusive.
Construct the probability distribution table for X.

EASY
AS and A Level
IMPORTANT

In a particular discrete probability distribution the random variable X takes the value 120r with probability r45, where r takes all integer values from 1 to 9 inclusive.

Which is the modal value of X ?