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**Question**

18)

A bag contains 20 discs.

10 are red, 7 are blue and 3 are green.

a) Marnie takes a disc at random before putting it back in the bag.

Nick then takes a disc at random before putting it back in the bag.

Olly then takes a disc at random.

Work out the probability that they all take a red disc.

A bag contains 20 discs.

10 are red, 7 are blue and 3 are green.

a) Marnie takes a disc at random before putting it back in the bag.

Nick then takes a disc at random before putting it back in the bag.

Olly then takes a disc at random.

Work out the probability that they all take a red disc.

**[2 marks]**

b)

All 20 discs are in the bag.

Work out the probability that all three discs are different colours.

All 20 discs are in the bag.

- Reggie takes three discs at random, one after the other.
- After he takes a disc he does
**not**put it back in the bag. Reggie’s first disc is blue.

Work out the probability that all three discs are different colours.

**[3 marks]**