Statistics

Elementary Statistics Name:

Study Guide 22 Class:

Due Date: Score:

No Work ⇔ No Points

Use Pencil Only ⇔ Be Neat & Organized

1. (2 points) What is the confidence interval?

1.

2. (2 points) What is the point-estimate?

2.

3. Use mathematical notation to give the point-estimate for

(a) (1 point) population proportion p.

(a)

(b) (1 point) population mean µ.

(b)

4. (2 points) What does the confidence level indicate?

4.

5. (2 points) What is the significance level?

5.

6. (1 point) What confidence level do we use if none is provided?

6.

Page 1 of 4 Study Guide 22 Total Points: 50

7. (2 points) Whenever constructing the confidence interval for population propor- tion, what TI commands do you use to find the C.V. and Confidence Interval? Be very specific about your answers.

7.

8. Find the following critical values.

Drawing, Shading, labeling & Full TI Command Required.

(a) (2 points) z0.015.

(a)

(b) (2 points) zα/2 for α = 0.03 significance level.

(b)

(c) (2 points) zα/2 for 97% confidence level.

(c)

9. Consider the confidence interval 0.568 < p < 0.724,

(a) (2 points) Find the sample proportion p̂.

(a)

(b) (2 points) Find the margin error for this confidence interval.

(b)

Page 2 of 4 Study Guide 22 Total Points: 50

10. Consider the confidence interval −.126 < p < 0.226,

(a) (2 points) Find the sample proportion p̂.

(a)

(b) (2 points) Find the margin error for this confidence interval.

(b)

11. Given n = 320 and x = 208,

(a) (2 points) find 99% confidence interval to estimate population proportion.

(a)

(b) (2 points) find the margin of error.

(b)

12. (3 points) Given n = 500 and p̂ = 0.38, find confidence interval to estimate popula- tion proportion.

12.

13. In a survey of 125 drivers, 70 of them admitted that they have texted while driving,

(a) (2 points) Find the 94% confidence interval for the proportion of all drivers that have texted while driving.

(a)

(b) (2 points) Find the margin of error for this confidence interval.

(b)

Page 3 of 4 Study Guide 22 Total Points: 50

14. Find the minimum sample size needed when estimating population proportion with 98% confidence level, margin of error to be within 4% and

(a) (2 points) p̂ = .75.

(a)

(b) (2 points) p̂ is unknown.

(b)

15. In a survey of 328 adults, 15% of them admitted that they have driven while intoxicated,

(a) (2 points) Find the 90% confidence interval for the proportion of all adults drivers that they have driven while intoxicated.

(a)

(b) (2 points) Find the minimum sample size needed if we wish to be 99% con- fident and error to be within 5% of the true proportion of all adults drivers that they have driven while intoxicated.

(b)

16. In a survey of 275 students, 28% of them admitted that they have texted while in class,

(a) (2 points) Find the 98% confidence interval for the proportion of all students that have texted while in class.

(a)

(b) (2 points) Find the margin of error for this confidence interval.

(b)

Page 4 of 4 Study Guide 22 Total Points: 50