Question

Sue has 2 biscuits in a tin. there are 12 plain biscuits, 5 chocolate biscuits and 3 currant biscuits. Sue takes at random 2 biscuits from the tin.Work out the probability that the two biscuits were not the same type

Answer 1

Answer:

111/190 ≈ 58.4%

Step-by-step explanation:

The probability that they are different is the opposite of the probability that they are the same.

The probability that they are the same is:

P(plain, plain) = (12/20) (11/19) = 132 / 380

P(chocolate, chocolate) = (5/20) (4/19) = 20 / 380

P(currant, currant) = (3/20) (2/19) = 6 / 380

P(same) = 132/380 + 20/380 + 6/380

P(same) = 158/380

P(same) = 79/190

Therefore, the probability that they are different is:

P(different) = 1 − 79/190

P(different) = 111/190

P(different) ≈ 58.4%