Bonus

A random sample of size 16 is taken from the populationand 95% confidence interval for the population mean is found to be (25, 35). Find thepopulation variance.

Question 21 options:

104

10

30

5

15

20

Bowling league members bowled at two different locations. At the location with oiled lane a sample of 35 bowling has mean score 205.5 and sample standard deviation 25.4. on the other hand, at the location with dry lanes, a sample of 35 bowling has mean score 185.0 and sample standard deviation is 18.4. Find pooled variance.

Question 20 options:

1029.86

32.09

491.86

22.178

68

19

A random sample of 250 families in City A revealed that 65 families had annual income over $100,000. Another random sample of 300 family from city B contained 45 families had annual income over $100,000. Find the point estimate of the difference of proportion between City A and City B.

Question 19 options:

0.11

0.10

0.14

0.12

0.13

18

A company is interested on average wages of employee and variance. A sample of 20 workers is taken and it is found that mean wage was $9.5 and sample standard deviation was. $1.30. Construct a 95% confidence interval for the population variance.

Question 18 options:

(1.029, 3.795)

(0.752, 2.773)

(1.79, 3.119)

(0.977, 3.605)

(0.79, 2.919)

17

For 5 degrees of freedom and 95% confidence level what are the two critical values (Chi-Square_(1-alpha/2) and Chi-Square_(alpha/2)) from chi-square table?

Question 17 options:

Chi-Square_(1-alpha/2)=1.145

Chi-Square_(alpha/2) =11.070

Chi-Square_(1-alpha/2)=1.610

Chi-Square_(alpha/2) = 9.236

Chi-Square_(1-alpha/2)=0.831

Chi-Square_(alpha/2) =12.833

Chi-Square_(1-alpha/2)= 0.831

Chi-Square_(alpha/2) =11.070

Chi-Square_(1-alpha/2)= 1.145

Chi-Square_(alpha/2) =12.833

16

If you want to find 90% confidence interval for mean. the critical value, Zalpha over2 = 1.65. If you want to find 80% confidence interval for mean. The critical value, Zalpha over2 will be......

Question 16 options:

1.96

2.58

1.285

2.98

3.27

15

Given, n=40 and sigma=2.0, alpha=5%, find the maximum error of the estimate for Mean.

Question 15 options:

0.72

0.92

0.62

0.52

0.82

14

Ten randomly selected automobiles were stopped, and the tread depth of the tire was measured. The sample mean was 0.32 inch and sample standard deviation was 0.08 inch. Find the 90% confidence Interval of the populationmean depth.

Question 14 options:

(0.27, 0.30)

(0.26, 0.29)

(0.25, 0.39)

(0.27, 0. 37)

(0.30, 0.40)

13

For the 95% confidence interval of mean sample size is 9 (sigma unknown). what is t-alpha over 2 (Critical value)?

Question 13 options:

2.306

2.262

2.365

2.896

1.860

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12

A researcher is interested in estimating the average monthly salary. With 92% confidence interval if the Standard deviation is $1100. How large a sample is needed to get the desired information with in $150?

Question 12 options:

15

165

45

147

207

11

How large a sample is necessary if we wish to estimate 95% confidence interval which is accurate within25% and population standard deviation is known to be 2 years.

Question 11 options:

2

9

16

11

246

10

A survey of 30 adults found that the mean age of a person's vehicle is 5.6 years. Assuming the population standard deviation is 0.8 years, find the 90% confidence interval of the population mean.

Question 10 options:

(4.31, 5.88)

(5.36, 5.84)

(6.78, 8.32)

(5.22, 7.98)

(6.32, 7.87)

9

A recent poll of 700 people who work indoors found that 278 of them smoke. If the researchers want to be 98% confident of their results to within 3.5%, how large a sample is necessary?

Question 9 options:

532

1301

461

1057

751

8

50 students are asked if they watched the super bowl and 20 saied yes. Find the pint estimate of proportion of students who watch super bowl

Question 8 options:

10%

30%

40%

20%

50%

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7

Using the z-table find the critical value (Zalpha/2)for a alpha= 14%

Question 7 options:

1.24

1.96

1.755

2.575

1.475

6

Which of the followingstatements is correct?

Question 6 options:

Point estimate of sample mean is population mean

Point estimate of population mean is sample mean

Point estimate of population mean ispopulation proportion

Point estimate of population mean is sample proportion

None of the given statements are correct.

5

How large a sample size is needed to determine the percentage of households using internet if we want to be 95% confident that the sample percentage is in error by no more than four percentage points.

Question 5 options:

601

501

201

101

301

4:

Alpha=20% the confidence interval for mu is found to be (110, 321). Which of the following statement(s) is true? (a) We are 20% sure that the actual mean is between 110 to 321. (b) We are 20% sure that the actual mean is outside the range of 110 to 321. (c) We are 90% sure that the actual mean is between 110 to 321. (d) We are 80% sure that the actual mean is between 110 to 321. (e) We are 10% sure that the actual mean is between 110 to 321.

Question 4 options:

(a)

(a) and (c)

both (b) and (d)

(c)

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3:

recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval of the true proportion of women in Europe who use the Internet?

Question 3 options:

(0.316,0.384)

(0.614,0.700)

(0.612,0.834)

(0.121,0.421)

(0.215,0.341)

Question 1

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000?

Question 1 options:

(0.148, 0.252)

(0.453,0.593)

(0.214,0.531)

(0.201,0.513)

(0.321,0.453)

Question 2:

To find critical value, whendo youuse t-table instead of z?

Question 2 options:

Whenpopulation mean is unknown butsample mean is known

When sample mean is unknown but population mean is known

When population standard deviation is known but sample standard deviation is unknown.

Whenpopulation varianceis unknown butsamplevariance is known

None of the given answers are correct.