Tute 5

In a rectangular distribution, a Z-score of 0 would be equivalent to the:

• a. 1st percentile

• b. 16th percentile

• c. 50th percentile

• d. 84th percentile

• e. 98th percentile

For a normal distribution with a mean of 40 and a standard deviation of 10, what is the approximate value of a score that would fall at the 95th percentile:

• a. 50

• b. 56

• c. 60

• d. 64

• e. 80

Answer explanation

X = Z σ + μ

X = 1.64 X 10 + 40

X = 56.4

When raw scores are transformed into Z-scores, then the Z-scores:

• a. Are normally distributed 

• b. Maintain the same mean and standard deviation as the raw scores

• c. Have no values below zero

• d. Have the same shaped distribution as the raw scores

• eWill add up to 1

Answer explanation

Which of the following is not true of a normal distribution?

• a. it is symmetrical about its mean

• b. the tails approach the X-axis asymptotically

• c. there is only a small percentage of scores in the tails of the distributions

• d. there is always 68.26% of the scores between Z=-1 and Z=+1

• e. the standard deviation of the scores is always the same

Answer explanation

In a positively skewed distribution, the sum of the Z-scores would be:

• a. zero

• b. greater than zero

• c. less than zero

• d. +1

• e. -1

Answer explanation

In a normal distribution, the percentage of scores between the mean and a score one standard deviation above the mean:

• a. Depends upon the value of the standard deviation

• b. is always a fixed percentage

• a. Depends upon the mean

• a. Depends on the interquartile range

• e. Depends upon the shape of the distribution

Which of the following does not apply to all distributions after conversion from raw scores to Z-scores?

• a. They always have a mean of 0

• b. They always have a standard deviation of 1

• c. They always have a variance of 1

• d. They are always normal

• e. c and d

Answer explanation