Question

pita has 12 coins in her bag there are three 1 pound coins and nine 50p coins she takes 3 coins out of the bag at random, work out the probability she takes out exactly £2.50

Answer 1

The probability of taking $ 2.5 is 12.2%

Explanation:

To make $ 2.5 with only 3 coins, you have to take out 2 $ 1 coins and a $ 0.5 coin in one of the following 3 ways:

(1) (1) (0.5) = (2.5) (i)

(1) (0.5) (1) = (2.5) (ii)

(0.5) (1) (1) = 2.5 (iii)

There are 3 coins (1)

There are 9 coins (0.5)

Therefore, the probability of drawing a coin from (1) on the first attempt is 3/12

The probability of drawing a coin of (0.5) on the first attempt is 9/12.

Then, the probability of drawing $ 2.5 from the form (i) is:

`P_((i))= (3)/(12)*(2)/(11)*(9)/(10) = 0.0409 = P_((ii)) = P_((iii))`

Finally:

P ($ 2.5) = P (i) U P (ii) U P (iii)

P ($ 2.5) = P (i) + P (ii) + P (iii)

P ($ 2.5) = 3P (i)

P ($ 2.5) = 3 * 0.0409

P ($ 2.5) = 12,227

The probability of taking $ 2.5 is 12.2%