Homework answers / question archive / 1)Find the critical value z?/2 that corresponds to a 98% confidence level

1)Find the critical value z?/2 that corresponds to a 98% confidence level

Statistics

Share With

---

1)Find the critical value z?/2 that corresponds to a 98% confidence level.              

A) 2.05  B) 2.33  C) 1.75  D) 2.575

 

 

2. Find the critical value z?/2 that corresponds to a 91% confidence level.                             

A) 1.645                B) 1.75  C) 1.34

                D) 1.70 

3.            Find the critical value z?/2 that corresponds to a 93% confidence level.  

A) 2.70

                B) 1.81  C) 1.96  D) 1.48

 

4. Find the value of z?/2 that corresponds to a confidence level of 89.48%.          

A) 0.0526             B) 1.62  C) - 1.62                D) 1.25

 

5.  Express the confidence interval 0.039 < p < 0.479 in the form of p^ ± E.            

A) 0.259 - 0.22    B) 0.259 ± 0.5     C) 0.22 ± 0.5        D) 0.259 ± 0.22

6.            Express the confidence interval 0.491 ± 0.057 in the form of p^ - E < p < p^ + E.  38)

A)           0.491 < p < 0.548               B) 0.434 < p < 0.491

C) 0.434 < p < 0.548 D) 0.4625 < p < 0.5195

 

Solve the problem.

7.            The following confidence interval is obtained for a population proportion, p: (0.688, 0.724). Use

these confidence interval limits to find the point estimate, p^ .

1. 0.708 B) 0.688 C) 0.724 D) 0.706

8.            The following confidence interval is obtained for a population proportion, p: 0.753 < p < 0.797. Use these confidence interval limits to find the point estimate, p^ .

A)           0.775     B) 0.770                C) 0.780                D) 0.753

 

9.            The following confidence interval is obtained for a population proportion, p: 0.724 < p < 0.752. Use these confidence interval limits to find the margin of error, E.

A)           0.015 B) 0.014 C) 0.028 D) 0.738

 

                10 The following confidence interval is obtained for a population proportion, p: (0.399, 0.437). Use these confidence interval limits to find the margin of error, E.

1. 0.019 B) 0.020 C) 0.017 D) 0.038

 

11. 95% confidence; n = 380, x = 50          43)

A)           0.0408   B) 0.0306              C) 0.0357              D) 0.0340

 

 

12.          95% confidence; the sample size is 9900, of which 30% are successes       

A) 0.0404             B) 0.0355              C) 0.0446

 

 

 

 

13.          98% confidence; the sample size is 800, of which 40% are successes          

A) 0.0348             B) 0.0306              C) 0.0293

D) 0.0385

14. 99% confidence; the sample size is 1110, of which 45% are successes                

A) 0.0252             B) 0.0241              C) 0.015

 

 

15.          In a random sample of 192 college students, 129 had part- time jobs. Find the margin of error for the 95% confidence interval used to estimate the population proportion.

A)           0.116     B) 0.00225           C) 0.0664              D) 0.0598

16. In a clinical test with 1600 subjects, 800 showed improvement from the treatment. Find the margin of error for the 99% confidence interval used to estimate the population proportion.

A)           0.0282 B) 0.0245 C) 0.0184 D) 0.0322

 

17.          n = 56, x = 30; 95% confidence    53)

A)           0.404 < p < 0.668               B) 0.426 < p < 0.646

C) 0.425 < p < 0.647         D) 0.405 < p < 0.667

 

 

 

 

18.  Margin of error: 0.005; confidence level: 96%; p^ and q^ unknown   58)

A) 42,148             B) 42,018              C) 32,024              D) 42,025

 

 

 

 

 

 

19. Margin of error: 0.008; confidence level: 98%; p^ and q^ unknown   

A) 21,207             B) 20,308              C) 10,384              D) 22,184

 

 

20. Margin of error: 0.04; confidence level: 95%; from a prior study, p^ is estimated by the decimal          65) equivalent of 60%.

A)           996         B) 1441 C) 577    D) 519

 

 

21. Margin of error: 0.04; confidence level: 99%; from a prior study, p^ is estimated by 0.12.              

A)           526         B) 18      C) 254    D) 438

22.                 Margin of error: 0.07; confidence level: 95%; from a prior study, p^ is estimated by the decimal equivalent of 92%.

A)           58           B) 4        C) 174    D) 51

23.                 Margin of error: 0.07; confidence level: 90%; from a prior study, p^ is estimated by 0.30.               

A)           103         B) 8        C) 348    D) 116

24.                 Margin of error: 0.007; confidence level: 99%; from a prior study, p^ is estimated by 0.255.               
    1. 1. 180 B) 14,895 C) 23,137 D) 25,708

 

25. Find the point estimate of the proportion of people who wear hearing aids if, in a random sample of 898 people, 46 people had hearing aids.
    1. 1. 0.050 B) 0.949 C) 0.051 D) 0.049
26. 32 randomly picked people were asked if they rented or owned their own home, 8 said they rented. Obtain a point estimate of the proportion of home owners.

A)           0.750     B) 0.250                C) 0.781                D) 0.200

 

 

27.                 445 randomly selected light bulbs were tested in a laboratory, 316 lasted more than 500 hours. Find a point estimate of the proportion of all light bulbs that last more than 500 hours.
    1. 1. 0.708 B) 0.290 C) 0.710 D) 0.415
28.                 50 people are selected randomly from a certain population and it is found that 12 people in the  sample are over 6 feet tall. What is the point estimate of the proportion of people in the population who are over 6 feet tall?
    1. 1. 0.18 B) 0.50 C) 0.24 D) 0.76

 

 

29. Construct the 95% confidence interval for the true proportion of all voters in the state who favor approval.

A) 0.471 < p < 0.472 B) 0.444 < p < 0.500

0.435 < p < 0.508 D) 0.438 < p < 0.505