Assume that 30.8% of people have sleepwalked. Assume that in a random sample of 1477 adults, 476 have sleepwalked. a. Assuming that the rate of 30.8% is correct, find the probability that 476 or more of the 1477 adults have sleepwalked. b. Is that result of 476 or more significantly high? c. What does the result suggest about the rate of 30.8%?
The the number of of people have sleepwalked
follows Binomial distribution with
The PMF of
is
a) The probability that 476 or more of the 1477 adults have sleepwalked is
Use R to find the above probability, the command is
> 1-pbinom(475,1477,0.308)
[1] 0.1232379
You can use Poisson approximation since is large with .
b) It is not high since its is less than 0.5. The PMF peaks around .
This is not included in the above probability.
c) The observation 476 suggests a rate . So the rate 30.8% is low.
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