Module 4 Chp 6 & 7

z = -1.28 and z = +1.28

At an organization, scoring in the middle 80% of employees regarding job performance is designated as satisfactory. Job performance is a normally distributed variable. Individuals designated as having satisfactory job performance would have job performance scores that correspond with z-scores equal to or between _____.

M is less than 36 for a sample of n = 100

For a normal population with µ = 40 and σ = 10, which of the following samples is least likely to be obtained?

µM = 60; σM = 10.

For a normal population with µ = 60 and σ = 50, the distribution of sample means based on n = 25 will have an expected value of ____ and a standard error of ____.

z = -0.17

If a sample of n = 4 scores is obtained from a normal population with µ = 70 and σ = 12, what is the z-score corresponding to a sample mean of M = 69?

if the population is normal or if the sample size is greater than 30

Under which circumstance will the distribution of sample means be normal?

X = 80

A highly selective university requires that applying students complete an entrance exam with µ = 60 and σ = 16. Applying students must avoid scoring in the bottom 89.5% of scores on the exam in order to be accepted into the university. Applicants must score more than _____ in order to be accepted to the university.

p = 0.7486

A normal distribution has a mean of µ = 50 with σ = 6. If one score is randomly selected from this distribution, which is the probability that the score will be greater than X = 46?

32.64%

A population is normally distributed with a mean of µ = 145 and σ = 20. Which is the percentile rank for X = 136?

90.32%

A population is normally distributed with µ = 145 and σ = 20. Which is the percentile rank for X = 171?

p = 0.2119

A random sample of n = 64 scores is obtained from a normal population with µ = 30 and σ = 10. What is the probability that the sample mean will be greater than M = 31?

The new exercise regimen has an effect on muscle strength because the computed z-score reaches the z = ±1.96 threshold.

A researcher develops a new exercise regimen for influencing muscle strength. The researcher knows that scores on a well-validated measure of muscle strength are normally distributed with µ = 15 and σ = 4. The researcher administers their new exercise regimen to a sample of n = 64 adults who subsequently score M = 16.5 on the measure of muscle strength. Which conclusion can the researcher make based on the results of this research study?

M = 52 and n = 81

A sample is selected from a normal population with µ = 54 and σ = 8. Which of the following samples would be considered extreme and unrepresentative for this population?

σM = 3

A sample of n = 49 scores with M = 43 is selected from a population with µ = 40 and with σ = 21. What is the standard error for the sample mean?

3 points

A sample of n = 64 scores is selected from a population with µ = 80 and with σ = 24. On average, how much error is expected between the sample mean and the population mean?

0.8849

A vertical line is drawn through a normal distribution at z = -1.20. What proportion of the distribution is on the right-hand side of the line?

5 points

If random samples, each with n = 16 scores, are selected from a normal population with µ = 100 and σ = 20, how much difference, on average, should there be between a sample mean and the population mean?

X = 84

Mitchell is getting ready to take a baseball rules exam in order to become certified as a baseball umpire in his local community. Past scores on the rules exam form a normal distribution with µ = 80 and σ = 6. Mitchell must score in the highest 25% of the distribution in order to become a certified umpire. Which minimum score does Mitchell need to obtain on the rules exam to become a certified umpire?

σM = 6

Samples of size n = 9 are selected from a normal population with µ = 80 and with σ = 18. What is the standard error for the distribution of sample means?

p = 0.1056

What is the probability of randomly selecting a z-score greater than z = +1.25 from a normal distribution?

the standard deviation of the distribution of sample means

Which is the standard error of M?