SOLUTION: Among 10 laptop computers, five are good and five have defects. Unaware of this, a customer buys 6 laptops. a) What is the probability of exactly 2 defective laptops among them?

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Question 1172933: Among 10 laptop computers, five are good and five have defects. Unaware of this, a customer buys 6 laptops.
a) What is the probability of exactly 2 defective laptops among them?
b) What is the probability of 3 defective and 3 good laptops among them
Found 2 solutions by ewatrrr, ikleyn:
Answer by ewatrrr(24785) About Me  (Show Source):
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Hi,

p = 1/2 , n = 10 , 5G, 5def

customer buys 6 laptops.

Probability of them being good or defective is the same

a) What is the probability of exactly 2 defective laptops among them?

P(2def) = (5C2)(5C4)/(10C6) = (10)(5)/(210)

b What is the probability of 3 defective and 3 good laptops among them

P(3 defective and 3 good laptops) = (5C3)(5C3)/(10C6) = (10)(10)/(210)

Answer by ikleyn(52802) About Me  (Show Source):
You can put this solution on YOUR website!
.
Among 10 laptop computers, five are good and five have defects. Unaware of this, a customer buys 6 laptops.
a) What is the probability of exactly 2 defective laptops among them?
b) What is the probability of 3 defective and 3 good laptops among them
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(a)  In this case, the customer gets 2 defective and 6-2 = 4 good laptops.


     The probability to have this selection is  

         P = %28C%5B5%5D%5E2%2AC%5B5%5D%5E4%29%2FC%5B10%5D%5E6 = %2810%2A5%29%2F210 = 5%2F21.



(a)  In this case, the customer gets 3 defective and 6-3 = 3 good laptops.


     The probability to have this selection is  

         P = %28C%5B5%5D%5E3%2AC%5B5%5D%5E3%29%2FC%5B10%5D%5E6 = %2810%2A10%29%2F210 = 10%2F21