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bethany7
Oct 4, 2012, 06:31 AM
20 tins of soup. 7 are tomato, 9 are potato, 4 are carot. 2 tins are chosen at rendom. What is the probability that they are both carrot?

Unknown008
Oct 4, 2012, 08:44 AM
What is your attempt?

bethany7
Oct 4, 2012, 10:39 AM
7/20 x 9/20 x 4/20 = 252/ 80000

Unknown008
Oct 5, 2012, 09:09 AM
The probability of getting the first as a carrot is given by:

Number of carrot soup cans / Total number of cans

The probability of getting the second as a carrot is given by:

Number of carrot soup cans left / Total number of cans left


The net probability is the product of those two probabilities.

Can you try again?



By the way, the probability that you have got above is the probability that you first pick a tomato soup can, then you pick a potato soup can after replacing the tomato can, and third get a carrot soup can after replacing the potato can.