2.3 Exam 4: chapters 8, 9, & 10  (Page 2/2)

What is meant by the term “95% confident” when constructing a confidence interval for a mean?

• A

  If we took repeated samples, approximately 95% of the samples would produce the same confidence interval.

• B

  If we took repeated samples, approximately 95% of the confidence intervals calculated from those samples would contain the sample mean.

• C

  If we took repeated samples, the sample mean would equal the population mean in approximately 95% of the samples.

• D

  If we took repeated samples, approximately 95% of the confidence intervals calculated from those samples would contain the true value of the population mean.

Find the 90% confidence interval for the true mean installation time using this new procedure.

• A

  (86.1, 97.9)

• B

  (86.9, 91.1)

• C

  (87.2, 96.8)

• D

  Not enough information

The value that is the center of the confidence interval is:

• A

  91

• B

  92

• C

  93

• D

  μ

The amount of soda contained in a can for a certain brand of soda is normally distributed with a population standard deviation of 0.1 ounces. A random sample of 40 cans of soda was selected and the amount of soda in each can was measured. The sample mean was 12.03 ounces and the sample standard deviation was 0.08 ounces.

What is the appropriate distribution to use when calculating a confidence interval for the true mean amount of soda contained in all cans of this brand?

• A

  The student-t distribution, because the sample standard deviation is given.

• B

  The student-t distribution, because the repair costs are approximately normally distributed.

• C

  The standard normal distribution, because the population standard deviation is known.

• D

  The standard normal distribution, because the sample mean is known.

What is the appropriate distribution to use when calculating a confidence interval for the true mean amount of soda contained in all cans of this brand?

• A

  m1<m2

• B

  m1>m2

• C

  m1 £ m2

• D

  m1 ³ m2

The exact distribution for the hypothesis test is:

• A

  The normal distribution because the population standard deviations are given.

• B

  The student-t distribution because the population standard deviations are unknown.

• C

  The exponential distribution because the time of delivery decreases.

• D

  Not able to determine.

f the p-value is 0.0056, the conclusion is:

• A

  The mean delivery time for the first company is higher than the mean delivery time for the second company.

• B

  The mean delivery time for the first company is no more than the mean delivery time for the second company.

• C

  The mean delivery time for the first company is at least equal to the mean delivery time for the second company.

• D

  The mean delivery time for the first company is less than the mean delivery time for the second company.

This is a test of:

• A

  Two independent population means, population standard deviations known.

• B

  Two independent population means, population standard deviations unknown.

• C

  Paired or matched samples.

• D

  Two population proportions.

The distribution for the hypothesis test is:

• A

  Student-t

• B

  Exponential

• C

  Normal

• D

  Uniform

A newspaper/TV network survey was conducted to determine whether the percentage of adult males who favor the death penalty is greater than the percentage of adult females who favor the death penalty. A random sample of 800 adult males produced 480 who favor the death penalty., while a random sample of 800 adult females produced 410 who favor the death penalty.

The Type I error is to:

• A

  Conclude that the percentage of adult males who favor the death penalty is greater than the percentage of adult females who favor the death penalty when, in fact, the percentage of males is no more than the percentage of females.

• B

  Conclude that the percentage of adult males who favor the death penalty is no more than the percentage of adult females who favor the death penalty when, in fact, the percentage of males is more than the percentage of females.

• C

  Conclude that the percentage of adult males who favor the death penalty is greater than the percentage of adult females who favor the death penalty when, in fact, the percentage of males is actually greater than the percentage of females.

• D

  Conclude that the percentage of adult males who favor the death penalty is no more than the percentage of adult females who favor the death penalty when, in fact, the percentage of males is actually no more than the percentage of females.