Question

1. A teacher is interested in what proportion of De Anza statistics students submit their homework on time. She randomly surveys 40 students and finds that 30 of them submit their homework on time.

For the confidence interval, if we repeated the study keeping the same level of confidence (95%) and increased the sample size, what would we expect to happen?

a. The error bound would increase.

b. The error bound would decrease.

c. The error bound would not change.

d. The interval must contain the true proportion.

2. A teacher is interested in what proportion of De Anza statistics students submit their homework on time. She randomly surveys 40 students and finds that 30 of them submit their homework on time.

The error bound for a 95% confidence interval for the true proportion of De Anza statistics students who submit their homework on time is:

a. 0.1126

b. 0.1342

c. 0.2252

d. 0.2684

3. A teacher is interested in what proportion of De Anza statistics students submit their homework on time. She randomly surveys 40 students and finds that 30 of them submit their homework on time.

The point estimate for the proportion of De Anza statistics students that submit their homework on time is:

a. 0.75

b. 0.30

c. 30

d. 0.40

4.A local birthing center believes that the length of human pregnancies (with no complications) from conception to birth lasts longer than 260 days. A random sample of 20 pregnancies lasted an average of 258 days with a standard deviation of 9.5 days.

Construct and interpret a 90% confidence interval for the true average length of human pregnancies.

a. We are 90% confident that the true average length is between 254.51 and 261.49 days.

b. We are 90% confident that the true average length is between 254.33 and 261.67 days.

c. 90% of all samples will give a confidence interval of between 254.33 and 261.67 days.

d. The length for 90% of all samples will be between 254.51 and 261.49 days.

5. A local birthing center believes that the length of human pregnancies (with no complications) from conception to birth lasts longer than 260 days. A random sample of 20 pregnancies lasted an average of 258 days with a standard deviation of 9.5 days.

A Type II error for this test would be to conclude that:

a. the true average length of pregnancies is less than 260 days, when it is really more.

b. the true average length of all pregnancies is more than 260 days, when it is really less.

c. the true average length of all pregnancies is at least 260 days, when it is really less.

d. the true average length of pregnancies is at most 260 days, when it is really more.

6. A local birthing center believes that the length of human pregnancies (with no complications) from conception to birth lasts longer than 260 days. A random sample of 20 pregnancies lasted an average of 258 days with a standard deviation of 9.5 days.

a. Ho: µ < 260, Ha: µ > 260

b. Ho: µ ≥ 260, Ha: µ < 260

c. Ho: µ ≥ 260, Ha: µ ≠ 260

d. Ho: µ ≤ 260, Ha: µ > 260

Answer 1