PSY 230 - Chapter 5

For a population with µ = 80 and σ = 10, what is the z score corresponding to X = 85?

+0.50

For a population with σ = 4, an individual with a deviation score of +2 would have a z-score of _____.

+0.50

A population of scores has µ = 42. In this population, an X value of 40 corresponds to z = −0.50. What is the population standard deviation?

4

For a population with µ = 60 and σ = 8, what is the X value corresponding to z = 1.50?

72

A population of scores has σ= 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean?

75

For a population with µ = 100 and σ = 20, what is the X value corresponding to z = −0.25?

95

For a sample with a mean of M = 70, what is the z-score corresponding to a score that is located 10 points below the mean?

Cannot answer without knowing the standard deviation

For a sample with M = 100 and s = 10, what is the score corresponding to z = 1.50?

X = 115

A distribution with µ = 35 and σ = 8 is being standardized so that the new mean and standard deviation will be µ = 50 and σ = 10. When the distribution is standardized, what value will be obtained for a score of X = 39 from the original distribution?

X = 55

For the past 20 years, the high temperature on April 15th has averaged µ = 62 degrees with a standard deviation of σ= 8. Last year, the high temperature was 66 degrees. Based on this information, last year's temperature on April 15th was _____.

a little above average

A z-score of z = −2.00 indicates a position in a distribution that is below the mean by a distance equal to 2 standard deviations. What position is indicated by a z-score of z = +1.00?

above the mean by a distance equal to 1 standard deviation

Under what circumstances would a score that is 15 points above the mean be considered an extreme score?

when the population standard deviation is much smaller than 15

In a distribution with μ = 60 and σ = 10 a score of X = 80 corresponds to a z-score of z = +2.00 because it is above the mean by exactly 2 standard deviations. For this same distribution, what is the z-score corresponding to X = 65?

z = +0.50

In a sample with M = 60 and s = 10 a score of X = 70 corresponds to a z-score of z = +1.00 because it is above the mean by exactly 1 standard deviation. For this same distribution, what is the z-score corresponding to X = 65?

z = +0.50

In a distribution with μ = 60 and σ = 10 a score of X = 45 is below the mean by exactly 1.50 standard deviations, which means that it corresponds to a z-score of z = −1.50. For this same distribution, what is the z-score corresponding to X = 70?

z = +1.00

A location that is above the mean by one half of a standard deviation is assigned a z-score of z = +0.50. What z-score is assigned to a location that is below the mean by one standard deviation?

z = −1.00

In a sample with a mean of M = 45 and a standard deviation of s = 5, a z-score of z = −2 corresponds to X = 35 because the score is below the mean by exactly 2 standard deviations. What is the z-score corresponding to X = 40?

z = −1.00

A population with µ = 85 and σ = 12 is transformed into z-scores. After the transformation, the population of z-scores will have a mean of _____.

µ = 0

For a distribution of exam scores with μ = 50, which value for the standard deviation would give the highest grade to a score of X = 45?

σ = 10