Author: Anonymous

Imagine that you conducted a hypothesis test examining how automobile ownership (i.e., someone owns an automobile or does not own an automobile) affects happiness (measured by a survey). You found that people who do not own automobiles tend to be significantly happier than those that do own an automobile. You then computed the effect size, d = 1.25. a) Why is it important to compute an effect size? b) Please interpret the Cohen’s d value (d = 1.25) by explaining what it means in terms of automobile ownership and happiness.

A sample of n = 16 scores is obtained from a population with µ = 50 and σ = 16.  If the sample mean is M = 54, then what is the z-score for the sample mean?

John drives to work each morning and the trip takes an average of 38 minutes.  The distribution of driving times is approximately normal with a standard deviation of 5 minutes.  For a randomly selected morning, what is the probability that John’s drive to work will take less than 35 minutes?

What proportion of a normal distribution is located between the mean and z = –0.40?

A jar contains 10 red marbles and 30 blue marbles.  A random sample with replacement of n = 3 marbles is selected from the jar.  If the first two marbles are both blue, what is the probability that the third marble will be red?

A sample of n = 100 scores is selected from a population with µ = 80 with σ = 20.  On average, how much error is expected between the sample mean and the population mean?

A random sample of n = 36 scores is selected from a population.  Which of the following distributions definitely will be normal?

The distribution of sample means ____.

A normal distribution has a mean of µ = 70 with σ = 12.   If one score is randomly selected from this distribution, what is the probability that the score will be greater than X = 79?

Find the standard error for a sample mean with n = 20 and σ = 6.28.