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In a large population of college-educated adults, the mean IQ is 112 with standard deviation 25....

In a large population of college-educated adults, the mean IQ is 112 with standard deviation 25. Suppose 100 adults from this population are randomly selected for a market research campaign.

What is the probability that the sample mean IQ is lower than 105?

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Expert Solution

Solution :

Given that,

mean = = 112

standard deviation = = 25

n = 100

= 112

=  / n = 25/ 100=2.5

P( < 105) = P[( - ) / < (105-112) / 2.5]

= P(z <-2.8 )

Using z table  

= 0.0026   

probability= 0.0026

orchestra answered 3 years ago
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