In: Statistics and Probability
In the following problem, check that it is appropriate to use
the normal approximation to the binomial. Then use the normal
distribution to estimate the requested probabilities.
What are the chances that a person who is murdered actually knew
the murderer? The answer to this question explains why a lot of
police detective work begins with relatives and friends of the
victim! About 63% of people who are murdered actually knew the
person who committed the murder.† Suppose that a detective file in
New Orleans has 68 current unsolved murders. Find the following
probabilities. (Round your answers to four decimal places.)
(a) at least 35 of the victims knew their murderers
(b) at most 48 of the victims knew their murderers
(c) fewer than 30 victims did not know their murderers
(d) more than 20 victims did not know their murderers
c)
P(X<30) = P(X<=29)
d)
P(X>20) = P(X>=21)
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