Question

In: Statistics and Probability

The marks on a statistics midterm test are normally distributed with a mean of 75 and...

The marks on a statistics midterm test are normally distributed with a mean of 75 and a standard deviation of 6. What is the probability that a sample of 50 exams has an average midterm test mark that is less than 70?

a. Virtually 0

b. 0.2033

c. -5.89

d. 0.2776

e. Virtually 1

Solutions

Expert Solution

Solution :

Given that ,

= 75

= / n = 6 / 50 = 0.85

P( < 70) = P(( - ) / < (70 - 75) / 0.85)

= P(z < - 5.88)

Using z table

= 0

Correct option is a.


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