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Suppose the random variable X records a randomly selected student’s score on a national test, where...

Suppose the random variable X records a randomly selected student’s score on a national test, where the population distribution for the score is normal with mean 70 and standard deviation 5. A simple random sample of 200 students is taken.

(a) What is the distribution of the sample mean score? Is this the exact distribution or an approximated distribution?

(b) What is the probability that the sample mean will exceed 71?

(c) What is the probability that the sample mean will be in the interval (69.5, 70.5)?

Math   Statistics-And-Probability   
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