SOLUTION: Hi I really need help answering couple of questions, please could someone explain them to me? 1) In a batch of a hundred light bulbs there are 5 bad bulbs. Inspectors inspects 1

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Question 14780: Hi I really need help answering couple of questions, please could someone explain them to me?
1) In a batch of a hundred light bulbs there are 5 bad bulbs. Inspectors inspects 10 at random. Compute probability of finding at least one defective light bulb.
2)Eighty percent of a population with coronary disease have chest pain symptoms and twenty five percent without the disease have chest pain symptoms. A person visits the doctor with the chest pain symptom, what are the probabilities of the following events?
a)person has coronary disease
b)person does not have coronary disease.
Answer by khwang(438) (Show Source):
You can put this solution on YOUR website!
1) In a batch of a hundred light bulbs there are 5 bad bulbs. Inspectors inspects 10 at random. Compute probability of finding at least one defective light bulb.
Sol:Prob of defective for each light bulb is 1/20.
Prob. that all of the 10 not defective is (19/20)[sup]10[/sup] = 0.599
probability of finding at least one defective light bulb
is 1- (19/20)[sup]10[/sup]. = 0.401

2)Eighty percent of a population with coronary disease have chest pain symptoms and twenty five percent without the disease have chest pain symptoms. A person visits the doctor with the chest pain symptom, what are the probabilities of the following events?
a)person has coronary disease
b)person does not have coronary disease.
Sol: If no further information
a) prob. the person having coronary disease
p = 0.8 / (0.8 + 0.25) = 0.76
b) prob. the person having no coronary disease
1- 0.76 = 0.24

Kenny