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MATH 534 WEEK 3 HOMEWORK
Scores on a certain exam are normally distributed with a mean of 90 and a variance of 25. What is the z-value for a score of 80?
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-0. Scores on a certain exam are normally distributed with a mean of 90 and a variance of 25. What is the probability of obtaining a score less than 80?
Which one of the following is not a characteristic of a normal distribution? Continuous Symmetrical about its mean Discrete Unimodal If the z -value of a given x value is positive, it means that. Probability of getting a value below x is negative The x value is above the mean of the distribution The value of x is positive The standard deviation of the distribution is negative
Assume a normal distribution and find the following probabilities. (Round the values of z to 2 decimal places. Round your answers to 4 decimal places.) (a) P ( x < 24 | μ = 27 and σ = 3) ANS 0. (b) P ( x ≥ 45 | μ = 30 and σ = 8) ANS 0. (c) P ( x > 28 | μ = 30 and σ = 5) ANS 0. (d) P (23 < x < 28 | μ = 25 and σ = 3) ANS 0. (e) P ( x ≥ 86 | μ = 70 and σ = 2.87) ANS 0 Suppose X is normally distributed with mean 50 and standard deviation 4, what is P (45 < X < 58)?
Suppose X is normally distributed with mean 20 and standard deviation 4 ,^ find^ the^ value^ x 0 such^ that^ P ( X^ ≥^ x 0 )^ =^0.^975.
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According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2,087 per hour. Suppose the operating costs of an MD-80 jet airliner are normally distributed with a standard deviation of $173 per hour. (Round the value of z to 2 decimal places. Round your answers to 2 decimal places.) (a) At what operating cost would only 20% of the operating costs be less? ANS 1939. (b) (b) At what operating cost would 65% of the operating costs be more? ANS 2019. (c) (c) What operating cost would be more than 85% of operating costs? ANS 2268.
sampling regulatory sampling
Suppose samples of size 100 are drawn randomly from a normal population that has a mean of 20 and a standard deviation of 5. What is the probability of observing a sample mean less than 19?
Suppose samples of size 100 are drawn randomly from a normal population that has a mean of 20 and a standard deviation of 5. What is the probability of observing a sample mean between 19 and 20.5?
Suppose samples of size 100 are drawn randomly from a normal population that has a mean of 20 and a standard deviation of 5. What are the values of the mean and the standard deviation of the distribution of the sample means? 200 and 0. 20 and 0. 20 and 5 20 and 0. 200 and 0. Suppose the age distribution in a city is as follows.
Over 65 18% A researcher is conducting proportionate stratified random sampling with a sample size of 300. Approximately how many people should he sample from each stratum? Number of people Under 18 66 18–25 54 26–50 102 51–65 (^24) Over 65 54 The Aluminum Association reports that the average American uses 56.8 pounds of aluminum in a year. A random sample of 50 households is monitored for one year to determine aluminum usage. If the population standard deviation of annual usage is 12.2 pounds, what is the probability that the sample mean will be each of the following? (Round the values of z to 2 decimal places. Round your answers to 4 decimal places.) a. More than 61 pounds- ANS 0, b. More than 57 pounds- ANS 0. c. Between 55 and 57 pounds- ANS 0. d. Less than 53 pounds-ANS 0. e. Less than 48 pounds- ANS 0
