Question

For confidence interval computations, if the sample size is increased, we expect the margin of error to: a. Increase b. Decrease c. stay the same

The company you work for produces automotive parts for GM. A certain machine that makes a cutout in a piece of steel averages a cut size of 203.2085 mm with a standard deviation of 0.2083 mm. A random sample of 66 is taken from the population. What is the distribution of the sample mean?

1. Approximately normal with mean 25.0132 and standard error 0.0256.

2. 68% of sample averages will fall between 203.0002 and 203.4168.

3. Approximately normal with mean 203.2085 and standard error 0.0256.

4. Approximately normal with mean 203.2085 and standard error 0.2083.

Data from 2011 show that 45.6% of all flights from IAH departed late. If an analyst takes a simple random sample of 400 flights, what can be said about the sampling distribution of the sample proportion of flights that departed late?

1. The sampling distribution will be approximately uniform with a mean of 45.6

2. The sampling distribution will be approximately normal with a mean of 0.456 and a standard deviation of

   0.025.

3. The sampling distribution will be approximately normal with a mean of 45.6 and a standard deviation of

   99.2.

4. The sampling distribution of the sample proportion will be binomial with p = .4 and n = 400.

You are interested in purchasing a new car. One of the many points you wish to consider is the resale value of the car after 5 years. Since you are particularly interested in a certain foreign sedan, you decide to estimate the resale value of this car with a 99% confidence interval. You manage to obtain data on 17 recently resold 5-year-old foreign sedans of the same model. These 17 cars were resold at an average price of $12,110 with a standard deviation of $600. Suppose that the interval is calculated to be (11685,12535). How could the sample size and the confidence coefficient be altered in order to guarantee a decrease in the width of the interval?

a.Keep the sample size the same but increase the confidence coefficient.
b. Decrease the sample size but increase the confidence coefficient.

c.Increase the sample size but decrease the confidence coefficient.
d. Increase the sample size and increase the confidence coefficient.

Answer 1