Question

In: Statistics and Probability

For a normal population with ? = 70 and ? = 12, find the following. (a)...

For a normal population with ? = 70 and ? = 12, find the following.

(a) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 36 scores?

(b) What is the probability of obtaining a sample mean greater than 73 for a sample of n = 9 scores?

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Expert Solution

a) given ? = 70 and ? = 12

probability of obtaining a sample mean

P( x>73) = x - ? / ? / sqrt(n)

             = 73-70 / 12 / sqrt(36)

             = 3/ 12/ 6

            = 3/2

             =1.5

P( x > 1.5) = 1? P( Z<1.5 )=1?0.9332=0.0668

b)

P( x>73) = x - ? / ? / sqrt(n)

             = 73-70 / 12 / sqrt(9)

             = 3/ 12/ 3

            = 3/4

             =0.75

P( x > 0.75) = 1? P( Z< 0.75 ) = 1?0.7734 = 0.2266


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