Conditional Probability

Question 1

Maya has 6 marbles in a bag.
4 of the marbles are green.
2 of the marbles are yellow.
Maya takes 2 marbles at random from the bag.
Work out the probability that Maya takes two marbles of the same colour.

Answer =

Question 2

Amir has 8 sweets in a jar.
5 of the sweets are orange.
3 of the sweets are purple.
Amir takes 2 sweets at random from the jar.
Work out the probability that Amir takes two sweets of the same colour.

Answer =

Question 3

Ella has 7 pencils in her desk.
3 of the pencils are black.
4 of the pencils are green.
Ella takes 2 pencils at random from the desk.
Work out the probability that Ella takes two pencils of the same colour.

Answer =

Question 4

Noah has 9 balls in a box.
6 of the balls are red.
3 of the balls are blue.
Noah takes 2 balls at random from the box.
Work out the probability that Noah takes two balls of the same colour.

Answer =

Question 5

Sophia has 10 beads in a box.
7 of the beads are white.
3 of the beads are black.
Sophia takes 2 beads at random from the box.
Work out the probability that Sophia takes two beads of the same colour.

Answer =

Q1

There are 12 sweets in a bag.
4 are orange flavoured and 8 are grape flavoured.
Two sweets are selected at random.
Calculate the probability that one sweet is orange and one sweet is grape.

Answer =

Q2

A jar contains 15 sweets.
6 are chocolate and 9 are caramel.
Two sweets are selected at random.
Calculate the probability that one sweet is chocolate and one is caramel.

Answer =

Q3

A packet contains 20 sweets.
5 are mint and 15 are cola.
Two sweets are selected at random.
Calculate the probability that one sweet is mint and one is cola.

Answer =

Q4

There are 8 sweets in a box.
3 are blueberry and 5 are raspberry.
Two sweets are selected at random.
Calculate the probability that one sweet is blueberry and one is raspberry.

Answer =

Q5

There are 18 sweets in a bag.
7 are mango and 11 are pineapple.
Two sweets are selected at random.
Calculate the probability that one sweet is mango and one sweet is pineapple.

Answer =

Question 1

There are $n$ marbles in a bag.
Four are red marbles and the rest are blue marbles.
Two marbles are taken from the bag at random.

(a) Find the probability, in terms of $n$, that both are red marbles.
(b) Find the probability, in terms of $n$, that both are blue marbles.

(a)

(b)

Question 2

A box contains $n$ balls.
Six are white balls and the rest are black balls.
Two balls are drawn at random.

(a) Find the probability that both are white.
(b) Find the probability that both are black.

(a)

(b)

Question 3

There are $n$ playing cards on a table.
Three are kings and the rest are not kings.
Two cards are chosen at random.

(a) Find the probability that both cards are kings.
(b) Find the probability that neither card is a king.

(a)

(b)

Question 4

A jar contains $n$ coins.
Eight are gold coins and the rest are silver coins.
Two coins are picked randomly.

(a) Find the probability that both coins are gold.
(b) Find the probability that both coins are silver.

(a)

(b)

Question 5

There are $n$ pens in a box.
Five are blue pens and the rest are red pens.
Two pens are taken at random.

(a) Find the probability that both pens are blue.
(b) Find the probability that both pens are red.

(a)

(b)