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In a large population of college-educated adults, the mean IQ is 118 with a standard deviation...

In a large population of college-educated adults, the mean IQ is 118 with a standard deviation of 20. Suppose 200 adults from this population are randomly selected for a market research campaign. The probability that the sample mean IQ is greater than 120 is Select one: a. 0.0001. b. 0.0790. c. 0.1230. d. 0.9210. e. Cannot be determined

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Expert Solution

Solution :

Given that ,

mean = = 118

standard deviation = = 20

n = 200

= 118 and

= / n = 20 / 200  = 1.4142

P( > 120) = 1 - P( < 120)

= 1 - P(( - ) / < (120 - 118) / 1.4142 )

= 1 - P(z < 1.412)

= 1 - 0.9210

= 0.0790

Probability = 0.0790

option b) is correct

orchestra answered 2 years ago
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