1. A survey by the American Chemical Society found that 90% of dollar bils in th
ID: 3229613 • Letter: 1
Question
1. A survey by the American Chemical Society found that 90% of dollar bils in the Us. are tainted with traces of cocaine. Suppose we select eight dollar bills at random, the number of these bills which are tainted with cocaine can be modeled as a binomial random variable, BB- (a) Construct a table for the probability distribution of this random variable. (b) Suppose in our sample of eight bills we find seven with traces of cocaine. Is this an unusually high number? 2. A survey found that 48% of Us. adults use a tax preparer to file their taxes. Suppose we select 20 US. sdults at random. (a) Find the probability that 12 or more of the people in this sample use a tax preparer (b) Among 20 Us, adults, is 12 an unusually large number of people who use a tax preparerrExplanation / Answer
1) Let X be the numberof tainted bills.It can be considered as binomia random variable with probability of success
With p =0.9, number of trials n = 8
b) It is not an unussual high number as the probability of this happening as mentioned is close to 0.4.
X P(X=x) 1 <0.000001 2 2.268E-05 3 0.000408 4 0.000459 5 0.03307 6 0.148803 7 0.38263 8 0.43047Related Questions
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