Business Statistics 1

The Central Limit Theorem says that the sampling distribution of the sample mean is approximately normal if

• all possible samples are selected.

• the sample size is large (n>30).

• the standard error of the sampling distribution is small.

The Central Limit Theorem says that the standard deviation of the sampling distribution of the sample means is

• equal to the population standard deviation divided by the square root of the sample size.

• close to the population standard deviation if the sample size is large.

• exactly equal to the standard deviation.

Z-score is used when _________ standard deviation is known?

• Population

• Sample

• None of the above

What assumptions are needed to use a T-interval?

• We can replace the population standard deviation σ by the sample standard deviation s.

• There are no assumptions needed.

• We have a random sample, and the data come from a normally distributed population.

• The sample size is large.

______ is used when population standard deviation is unknown and the sample size is small?

• T-score

• Z-score

• None of the above

The values associated with a two-sided 95% confidence interval of the standard normal distribution are

• A. ± 1.28

• B. ± 1.645

• C. ± 1.96

• D. ± 2.575

The values associated with a two-sided 90% of the Student’s t distribution and 73 degrees of freedom are

• A. ± 1.319

• B. ± 1.96

• C. ± 2.96

• D. ± 1.67

In general, how does doubling the sample size change the confidence interval size?

• Doubles the interval size

• Halves the interval size

• Multiplies the interval size by 1.414

• Divides the interval size by 1.414

If P(A) = 1/5, P(B) = 0, then what will be the value of P(A|B)?

• 0

• 1

• Not defined

• 1/5