Intelligence scores are distributed approximately normally with μ = 100 and σ = 15. In each...

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Intelligence scores are distributed approximately normally with μ = 100 and σ = 15. In each...

Intelligence scores are distributed approximately normally with μ = 100 and σ = 15. In each
part of this question, use two places after the decimal point for z scores and four places after the decimal point
for proportions. For each part (except part e), include an appropriate sketch

a) What proportion of intelligence scores is lower than 90?

b) What proportion of means of random samples of 9 intelligence scores is lower than 90?

c) What proportion of means of random samples of 25 intelligence scores is lower than 90?

d) What proportion of means of random samples of 100 intelligence scores is lower than 90?

e) As the sample size _______________________, the proportion of means of random samples at least some
distance from μ ____________________________

f) How low must an intelligence score be to be in the lowest 15%?

g) How low must the mean of a random sample of 9 intelligence scores
be to be in the lowest 15%?

h) How low must the mean of a random sample of 25 intelligence
scores be to be in the lowest 15%?

i) How low must the mean of a random sample of 100 intelligence
scores be to be in the lowest 15%?

math Statistics-And-Probability

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