Free Printable Confidence Interval and MOE

Worksheets

Confidence Interval and MOE

Total questions: 18

Worksheet time: 5hrs 30mins

Name

Class

Date

Suppose that $51,759 was the median income for all households in 2012. Does the interval ($51,484, $52,394) provide convincing evidence that the median household income increased in 2013?

Yes

A sample size of n = 64 is drawn from a population whose standard deviation is σ = 5.6.

Find the margin of error for a 99% confidence interval for µ.

1.799

1.798

1.803

We want to know if students work too much (and thus spend less time on their classes). Previous studies show that the standard deviation for work time is 3 hours, and a survey of 40 students has a mean of 9.8 work hours.

The 95% confidence interval is…

(8.84, 10.76)

(8.87, 10.73)

(9.02, 10.58)

(9.00, 10.60)

Suppose that a confidence interval for hours worked by students was computed to be (8.82, 10.78). Which of these is a valid interpretation of this confidence interval?

There is a 95% probability that the average number of hours worked by all students is between 8.82 and 10.78 hours.

There is a 95% probability that a randomly selected student worked between 8.82 and 10.78 hours.

We are 95% confident that the population average number of hours worked by all students is between 8.82 and 10.78 hours.

We are 95% confident that the average number of hours worked by the students in our sample is between 8.82 and 10.78 hours.

A factory that produces manhole covers took a random sample of 800 manhole covers and found that 40 out of the covers were defective. What is the 95% CI for the proportion of defective manhole covers?

(37.26, 42.74)

(.035, .065)

(.047, .053)

(.015, .085)

We wish to obtain a 95% confidence interval for the average SAT score for Midlo students. The standard deviation of all SAT scores is 180. We should sample (a) students if we wish the margin of error to be within 40 points. ROUND ANSWER TO THE NEAREST TEN (for example, 20, 120, etc.)

We plan to survey college seniors to see what proportion plan to attend grad school next year. Using 98% confidence, how many students should we survey if we wish the margin of error to be within 3%?

approximately 1170

approximately 1500

approximately 1050

approximately 40

The symbol for the sample proportion is __________.

Z_c

p̂

Which z-value is used for a 95% confidence interval?

1.65

1.96

2.58

2.33

10.

In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a sample standard deviation of $950. Construct a 99% confidence interval for the repair cost.

(1069.77, 2530.23)

(1077.13, 2522.87)

(1167.15, 2432.85)

None of these.

11.

A sample of 40 people owned an average of 1.35 apple products. It is known from a previous study that the population standard deviation of apple product ownership is 0.63 products. Construct a 95% confidence interval.

(1.11, 1.58)

(1.15, 1.55)

(1.19, 1.51)

(1.09, 1.61)

12.

A population has a standard deviation of σ = 17.3. How large of a sample must be drawn so that a 95% confidence interval for µ will have a Margin of Error equal to 1.4?

586.6

587

586

585

13.

Which of the following changes to a study would result in a narrower confidence interval?

increasing the confidence level, increasing the sample size

decreasing the confidence level, decreasing the sample size

increasing the confidence level, decreasing the sample size

decreasing the confidence level, increasing the sample size.

14.

It was found that in a sample of 90 teenage boys, 70% of them have received speeding tickets. What is the 90% confidence interval of the true proportion of teenage boys who have received speeding tickets?

(0.621, 0.780)

(0.591, 0.812)

(0.584, 0.830)

(0.615, 0.805)

15.

Which of the following values below represents the critical value for a 98% confidence interval?

2.326

2.054

1.645

3.091

16.

A sample of 25 different payroll departments found that the employees worked an average of 310.3 days a year with a standard deviation of 23.8 days. What is the 90% confidence interval for the average days worked of all payroll departments?

301.0 < μ < 319.6

298.0 < μ < 322.6

302.4 < μ < 318.2

314.1 < μ < 316.8

17.

A sample of 23 European countries found that the mean life expectancy was 80 years with a standard deviation of 7.3. What is the 95% confidence interval for the mean life expectancy in Europe?

55.349 < μ < 95.873

64.983 < μ < 89.368

76.843 < μ < 83.157

70.384 < μ < 80.563

18.

Construct a 95% confidence interval for the population mean, μ. Assume the population has a normal distribution. A sample of 20 college students had mean annual earnings of $3120 with a standard deviation of $677.

($2657, $2891)

($2803, $3437)

($1324, $1567)

($2135, $2567)

100 %

Confidence Interval and MOE

Total questions: 18

Worksheet time: 5hrs 30mins

Similar Resources on Wayground