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A bag contains 4 blue discs and 2 red discs. A disc is chosen at random from the bag and not returned. A second disc is then chosen from the bag.

 

Find the probability that The first disc is red and the second disc is blue

 

One disc is blue and the orther disc is red in any order 

 Apr 10, 2019
 #1
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First disc red   2 out of 6 chance     2/6       The disc is not returned , so there is only 5 left in the bag:

Second disc blue   4 out of 5 chance  4/5

2/6 * 4/5 = 8/30 = 4/15

 

 

Not positive about the second part but there are only 2 possibilities    red blue   (which we already calc'd above )  and  blue red 

 

First blue   4/6

Second red 2/5     4/6 * 2/5 = 8/30 = 4/15

 added to the first result   4/15 + 4/15 = 8/15  for  any order

 Apr 10, 2019
edited by ElectricPavlov  Apr 10, 2019

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