Question

1. Let X be a continuous random variable such that when x = 10, z = 0.5. This z-score tells us that x = 10 is less than the mean of X.

Select one:

• True
• False

2. If an economist wants to determine if there is evidence that the average household income in a community is different from $ 32,000, then a two-tailed hypothesis test should be used.

Select one:

• True
• False

3. α (alpha) refers to the proportion of the area that is outside the confidence interval.

Select one:

• True
• False

4. For a probability density function (PDF), the graph must coincide with or be below the horizontal axis for all possible values of the random variable.

Select one:

• True
• False

5. Determine the area under a standard normal curve to the left of z = -1.25.

Select one:

• a.    0.6978
• b.    0.7887
• c.     0.1056
• d.     0.8944

6. For a standard normal curve, which of the alternatives is closest to the Z value for the 90th percentile?

Select one:

• a.     -1.28
• b.     -0.82
• c.      1.28
• d.     0.82

7. The t-value that you would use to construct a 90% confidence interval for the mean with a sample of size n = 10 would be

Select one:

• a.     -1.8331
• b.     1.8331
• c.      0.7778
• d.       0.5770

Answer 1

1). Let X be a continuous random variable such that when x = 10, z = 0.5. This z-score tells us that x = 10 is less than the mean of X

Ans : false.

2)If an economist wants to determine if there is evidence that the average household income in a community is different from $ 32,000, then a two-tailed hypothesis test

Ans: true.

3) α (alpha) refers to the proportion of the area that is outside the confidence interval

Ans: True.

4). For a probability density function (PDF), the graph must coincide with or be below the horizontal axis for all possible values of the random variable

Ans: false.

5)Determine the area under a standard normal curve to the left of z = -1.25.

Ans: option (c) is correct     0.1056

6)For a standard normal curve, which of the alternatives is closest to the Z value for the 90th percentile?

Ans: option (c) is correct (ie. 1.28)

7)The t-value that you would use to construct a 90% confidence interval for the mean with a sample of size n = 10 would be

Ans: option (b) is correct.(i.e 1.8331)

Thanks!