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Author Question: Scores on a recent national statistics exam were normally distributed with a mean of 80 and a ... (Read 52 times)

penza

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on: Jun 24, 2018
Scores on a recent national statistics exam were normally distributed with a mean of 80 and a standard deviation of 6.
 a. What is the probability that a randomly selected exam will have a score of at least 71?
  b. What percentage of exams will have scores between 89 and 92?
  c. If the top 2.5 of test scores receive merit awards, what is the lowest score eligible for an award?
 d. If there were 334 exams with scores of at least 89, how many students took the exam?

Question 2

A random sample of 81 students at a local university showed that they work an average of 100 hours per month. The population standard deviation is known to be 27 hours. Compute a 95 confidence interval for the mean hours per month all students at the university work.


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ynlevi

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Reply #1 on: Jun 24, 2018
Answer to Question 1

a. .9332
b. 4
c. 91.76
d. 5,000

Answer to Question 2

94.12 to 105.88


penza

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Reply 2 on: Jun 24, 2018
Great answer, keep it coming :)

ttt030911

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Reply 3 on: Yesterday
Wow, this really help

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