ISS (Statistical Services) Statistics Paper I (New 2016 MCQ Pattern): Questions 283  285 of 469
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Question number: 283
» Probability » Bayes' Theorem and Applications
Question
Suppose a certain drug test is 99 % sensitive and 99 % specific, that is, the test will correctly identify a drug user as testing positive 99 % of the time, and will correctly identify a nonuser as testing negative 99 % of the time. Let’s assume a corporation decides to test its employees for drug use, and that only 0.5 % of the employees actually use the drug. The probability that, given a positive drug test, an employee is actually a drug user is conducted using Bayes’ theorem. Can we say Bayes’ theorem gives correct result?
Choices
Choice (4)  Response  

a.  Information insufficient 

b.  Yes always 

c.  Not always 

d.  Can’t make any claim 

Question number: 284
» Probability » Probability Distributions » Negative Binomial
Question
In a sequence of independent Bernoulli trails, if denotes the number of failures before (fixed) success, then the expected value of will be ________
Choices
Choice (4)  Response  

a. 


b. 


c. 


d.  Question does not provide sufficient data or is vague 

Question number: 285
» Probability » Probability Distributions » Poisson
Question
Twenty sheets of copper alloy were examined for surface flaws. The frequency of the number of sheets with a given number of flaws per sheet was as follows:
Number of flaws  Frequency 
0  4 
1  3 
2  5 
3  2 
4  4 
5  1 
What is the probability of finding a sheet chosen at random which contains 3 or more surface flaws?
Choices
Choice (4)  Response  

a. 


b. 


c. 


d.  Question does not provide sufficient data or is vague 
