SOLUTION: A store is selling 100 notebooks. 36 yellow notebooks, 42 blue notebooks and 22 red notebooks. A customer buys one notebook. A second customer, buys a notebook too. What is the pro

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Question 1172791: A store is selling 100 notebooks. 36 yellow notebooks, 42 blue notebooks and 22 red notebooks. A customer buys one notebook. A second customer, buys a notebook too. What is the probability that the second customer would buy? :
1. A yellow notebook?
2. A red notebook?
3. A blue notebook if the first customer bought yellow notebook?
Found 2 solutions by ewatrrr, ikleyn:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi  

100 NBs: 36Y, 42B, 22R

What is the probability that the second customer would buy? :

1. A yellow notebook? 

1st either buys a different color or a yellow one as well

P = %2864%2F100%29%2836%2F99%29 + %2836%2F100%29%2835%2F99%29 = %282309+%2B+1260%29%2F9900 = .3605

2. A red notebook? 

1st either buys a different color or a red one as well

P = %2878%2F100%29%2822%2F99%29 + %2836%2F100%29%2835%2F99%29=%281716+%2B+1260%29%2F9900 = .3006

3. A blue notebook if the first customer bought yellow notebook?

P(1st Y and 2nd B) = %2836%2F100%29%2842%2F99%29 = %281512%29%2F9900 .1528

Wish You the Best in your Studies.

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
A store is selling 100 notebooks. 36 yellow notebooks, 42 blue notebooks and 22 red notebooks. A customer buys one notebook.
A second customer, buys a notebook too. What is the probability that the second customer would buy? :
1. A yellow notebook?
2. A red notebook?
3. A blue notebook if the first customer bought yellow notebook?
~~~~~~~~~~~~~~


            In this problem,  ALL  THE  DATA  are in place to solve it. 


(1)  P(2nd buys yellow) = P(1st buys yellow, 2nd buys yellow) + P(1st buys blue, 2nd buys yellow) + P(1st buys red, 2nd buys yellow) = 


                        =      %2836%2F100%29%2A%2835%2F100%29                  +    %2842%2F100%29%2A%2836%2F100%29                  +   %2822%2F100%29%2A%2836%2F100%29 = 


                        =      %2836%2A35+%2B+42%2A36+%2B+22%2A36%29%2F10000 = 3564%2F10000 = 0.3564.       ANSWER


So, I answered question 1.



If you do understand the logic of my solution  (which is crystally clear),

you should be able to solve/answer question  2   ON  YOUR  OWN,   using  THE  SAME  LOGIC.