1.2 Skills practice exam 3: chapters 7, 8, 9, & 10

The alternate hypothesis is:

• A

  mCS = mB

• B

  mCS¹mB

• C

  mCS<mB

• D

  mCS>mB

The exact distribution for the test is:

• A

  Normal

• B

  Student-t with df»72.9775

• C

  Exponential

• D

  Uniform

The p-value is

• A

  0.0452

• B

  2.0376

• C

  0.0226

• D

  0

The point estimate of the population average amount of time teenagers spend on the Internet each day is

• A

  0.78 hours

• B

  32 hours

• C

  3.2 hours

• D

  unknown

An 87% confidence interval for the average amount of time a teenager spends on the Internet each day would be

• A

  (2.71, 3.68)

• B

  (2.83, 3.57)

• C

  (2.64, 3.76)

• D

  (2.79, 3.61)

Which of the following is TRUE about a 99% confidence interval for the true average amount of time that teenagers spend on the Internet each day?

• I

  We are 99% confident that the true average time that teenagers spend on the Internet per day lies within the confidence interval.

• Ii

  The confidence interval contains 99% of the data values collected.

• Iii

  99% of all the confidence intervals constructed this way contain the true average amount of time teenagers spend on the Internet each day.

• A

  I, II, and III

• B

  I and II

• C

  I and III

• D

  I only

The margin of error (error bound) for a 92% confidence interval for the true proportion of registered voters who actually voted in the last primary election is

• A

  0.0176

• B

  0.3900

• C

  0.3551

• D

  0.0349

Suppose you want to redo the survey of registered voters to see how many voted in the last election but this time you survey 1000 registered voters and find 340 voted in the last election. If the confidence level is maintained at 92% what happens to the confidence interval.

• A

  The confidence interval gets wider.

• B

  The confidence interval gets narrower.

• C

  The confidence interval stays the same.

• D

  The confidence interval cannot be calculated.

A study of a certain brand of AA batteries yielded a sample mean lifetime of 450 minutes with a sample standard deviation of 92 minutes. A hypothesis test was performed using the following hypotheses:

$H_{\mathrm{o}}$ : m = 480

$H_{\mathrm{a}}$ : m<480

The type I error for this hypothesis test is:

• A

  to conclude that the average battery lifetime is less than 480 minutes when, in reality, it is equal to 480 minutes

• B

  to conclude that the average battery lifetime is equal to 480 minutes when, in reality, it actually is equal to 480 minutes

• C

  to conclude that the average battery lifetime is equal to 480 minutes when, in reality, it is less than 480 minutes

• D

  to conclude that the average battery lifetime is greater than 480 minutes when, in reality, it is equal to 480 minutes