<PRE><B>Question 14780</B>
 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</PRE>