Question

Sue has 20 biscuits in a tin There are 12 plain biscuits 5 chocolate biscuits 3 currant biscuits Sue takes at 2 random biscuits from the tin Work out the probability that the 2 biscuits were not the same time

Answer 1

Answer:

111 / 190

Step-by-step explanation:

Total biscuits = 20

Plain, P = 12

Chocolate, C = 5

Currant, K = 3

Assume without replacement :

Probability that biscuit are of the same type :

P(plain) :

12 / 20 * 11 / 19 = 132 / 380

P(chocolate) :

5/ 20 * 4 / 19 = 20/ 380

P(currant) :

3/20 * 2 /19 = 6 / 380

Therefore,

Probability that biscuit is of the same type :

P(plain) + P(chocolate) + P(currant)

132/380 + 20/380 + 6/380

158 / 380 = 79 / 190

Therefore, probability that biscuit aren't of the same type :

1 - P(biscuit is of same type)

1 - 79/190

(190 - 79) / 190

111 / 190