I have statistics question need to be solved

2# A random sample of 332 medical doctors showed that 166 had a solo practice.

(a) Let p represent the proportion of all medical doctors who have a solo practice. Find a point estimate for p. (Use 3 decimal places.)
 
(b) Find a 98% confidence interval for p. (Use 3 decimal places.)

(e) What is the margin of error based on a 98% confidence interval? (Use 3 decimal places.)

3# In a marketing survey, a random sample of 730 women shoppers revealed that 640 remained loyal to their favorite supermarket during the past year (i.e., did not switch stores).

(a) Let p represent the proportion of all women shoppers who remain loyal to their favorite supermarket. Find a point estimate for p. (Use 3 decimal places.)
  
(b) Find a 95% confidence interval for p. (Use 3 decimal places.)

(d) As a news writer, how would you report the survey results regarding the percentage of women supermarket shoppers who remained loyal to their favorite supermarket during the past year?

Report p̂ along with the margin of error.

Report p̂.    

Report the margin of error

(e) What is the margin of error based on a 95% confidence interval? (Use 3 decimal places.)

4# In a marketing survey, a random sample of 994 supermarket shoppers revealed that 274 always stock up on an item when they find that item at a real bargain price.

(a) Let p represent the proportion of all supermarket shoppers who always stock up on an item when they find a real bargain. Find a point estimate for p. (Use 3 decimal places.)
 
(b) Find a 90% confidence interval for p. (Use 3 decimal places.)

(c) What is the margin of error based on a 90% confidence interval? (Use 3 decimal places.)

5# A New York Times/CBS poll asked the question, "What do you think is the most important problem facing this country today?" It found that seventeen percent of the respondents answered "crime and violence." The margin of sampling error was plus or minus 2.8 percentage points. Following the convention that the margin of error was based on a 95% confidence interval, find the 95% confidence interval for the percentage of the population that would respond "crime and violence" to the question asked by the pollsters. (Express answers as decimal numbers to 3 places.)

6# A random sample of medical files is used to estimate the proportion p of all people who have blood type B.

(a) If you have no preliminary estimate for p, how many medical files should you include in a random sample in order to be 80% sure that the point estimate p̂ will be within a distance of 0.034 from p? 
 
(b) Answer part (a) if you use the preliminary estimate that about 12 out of 90 people have blood type B. 

7# How hard is it to reach a businessperson by phone? Let p be the proportion of calls to businesspeople for which the caller reaches the person being called on the first try.

(a) If you have no preliminary estimate for p, how many business phone calls should you include in a random sample to be 99% sure that the point estimate p̂ will be within a distance of 0.062 from p? 
 
(b) A report states that business-people can be reached by a single phone call approximately 16% of the time. Using this national estimate for p, answer part (a). 

8# The National Council of Small Businesses is interested in the proportion of small businesses that declared Chapter 11 bankruptcy last year. Since there are so many small businesses, the National Council intends to estimate the proportion from a random sample. Let p be the proportion of small businesses that declared Chapter 11 bankruptcy last year.

(a) If no preliminary sample is taken to estimate p, how large a sample is necessary to be 99% sure that a point estimate p̂ will be within a distance of 0.088 from p? 
 
(b) In a preliminary random sample of 30 small businesses, it was found that twelve had declared Chapter 11 bankruptcy. How many more small businesses should then be included in a sample to be 99% sure that a point estimate p̂ will be within a distance of 0.088 from p? 

9#The National Council of Small Businesses is interested in the proportion of small businesses that declared Chapter 11 bankruptcy last year. Since there are so many small businesses, the National Council intends to estimate the proportion from a random sample. Let p be the proportion of small businesses that declared Chapter 11 bankruptcy last year.

(a) If no preliminary sample is taken to estimate p, how large a sample is necessary to be 99% sure that a point estimate p̂ will be within a distance of 0.088 from p? 
 
(b) In a preliminary random sample of 30 small businesses, it was found that twelve had declared Chapter 11 bankruptcy. How many more small businesses should then be included in a sample to be 99% sure that a point estimate p̂ will be within a distance of 0.088 from p? 

16# The U.S. Geological Survey compiled historical data about Old Faithful Geyser (Yellowstone National Park) from 1870 to 1987. Let x1 be a random variable that represents the time interval (in minutes) between Old Faithful eruptions for the years 1948 to 1952. Based on 8940 observations, the sample mean interval was x1 = 65.0 minutes. Let x2 be a random variable that represents the time interval in minutes between Old Faithful eruptions for the years 1983 to 1987. Based on 25,106 observations, the sample mean time interval was x2 = 72.2 minutes. Historical data suggest that σ1 = 8.07 minutes and σ2 = 12.13 minutes. Let μ1 be the population mean of x1 and let μ2 be the population mean of x2.

(a) Compute a 99% confidence interval for μ1 – μ2. (Use 2 decimal places.)

19# Determine the required sample size to estimate a population proportion with a Confidence Level of 90% and E = 0.054. 

20# Determine the required sample size to estimate a population proportion with a Confidence Level of 85% and E = 0.040. 

21# Determine the required sample size to estimate a population proportion with a Confidence Level of 95% and E = 0.120. 

22# Find the lower & upper limits of a confidence interval if the mean is sixteen percent, and the margin of error is 0.034. 
(Express answers as decimal numbers to 3 places.)

23# Given a random sample of size 320. Find a 99% confidence interval for the population proportion if the number of successes was 168. 
(Use 3 decimal places.)

24# Given a random sample of size 738. Find a 98% confidence interval for the population proportion if the number of successes is 622. 
(Use 3 decimal places.)

26# Five hundred seventeen (517) homes in a certain southern California community are randomly surveyed to determine if they meet minimal earthquake preparedness recommendations. One hundred seventy-seven (177) of the homes surveyed met the minimum recommendations for earthquake preparedness and 340 did not.
Find the point estimate for the population proportion of homes that do not meet the minimum recommendations for earthquake preparedness. (Round your answer to four decimal places.)

27#Five hundred fourteen (514) homes in a certain southern California community are randomly surveyed to determine if they meet minimal earthquake preparedness recommendations. One hundred seventy-one (171) of the homes surveyed met the minimum recommendations for earthquake preparedness and 343 did not.
Find the confidence interval at the 90% confidence level for the true population proportion of southern California community homes meeting at least the minimum recommendations for earthquake preparedness. (Round your answers to three decimal places.)

  ,  

28# According to a Field Poll conducted, 79% of adults (actual results are 400 out of 506 surveyed) feel that "education and our schools" is one of the top issues facing the state. We wish to construct a 90% confidence interval for the true proportion of adults who feel that education and the schools is one of the top issues facing the state.
Find a 90% confidence interval for the population proportion. Round your answers to three decimal places.
  ,  

29# According to a Field Poll conducted, 79% of adults (actual results are 400 out of 506 surveyed) feel that "education and our schools" is one of the top issues facing the state. We wish to construct a 90% confidence interval for the true proportion of adults who feel that education and the schools is one of the top issues facing the state.
What is a point estimate for the true population proportion? Express to two decimal places.

33# Marketing companies are interested in knowing the population percent of women who make the majority of household purchasing decisions. 
When designing a study to determine this population proportion, what is the minimum number you would need to survey to be 90% confident that the population proportion is estimated to within 0.05? (Round your answer up to the nearest whole number.) 
 women

37# Resistance training is a popular form of conditioning aimed at enhancing sports performance and is widely used among high school, college, and professional athletes, although its use for younger athletes is controversial. A random sample of 4130patients (age 8–30) admitted to U.S. emergency rooms with the code "weightlifting" were obtained. These injuries were further classified as "accidental" if caused by dropped weight or improper equipment use. Of the 4130 weightlifting injuries, 1540 were classified as accidental. 
Give a 90% confidence interval for the proportion of weightlifting injuries in this age group that were accidental. Round your answers to three decimal places. 
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44# A study of the effect of exposure to color (red or blue) on the ability to solve puzzles used 42 subjects. Half the subjects (21) were asked to solve a series of puzzles while in a red-colored environment. The other half were asked to solve the same series of puzzles while in a blue-colored environment. The time taken to solve the puzzles was recorded for each subject. To compare the mean times for the two groups of subjects using statistical procedures, what is the degrees of freedom? 
d.f. 

45# A study of commuting times reports the travel times to work of a random sample of 1076 employed adults in Chicago. The mean is x = 35.0 minutes and the standard deviation is s = 56.9 minutes. What is the standard error of the mean? (Round your answer to four decimal places.) 
 minutes

47# A random sample of 364 married couples found that 294 had two or more personality preferences in common. In another random sample of 584 married couples, it was found that only 40 had no preferences in common. Let p1 be the population proportion of all married couples who have two or more personality preferences in common. Let p2 be the population proportion of all married couples who have no personality preferences in common.

(a) Find a 95% confidence interval for p1 – p2. (Use 3 decimal places.)

48# Independent random samples of professional football and basketball players gave the following information. Assume that the weight distributions are mound-shaped and symmetric.

Weights (in lb) of pro football players: x1; n1 = 21

Weights (in lb) of pro basketball players: x2; n2 = 19

(a) Calculate the means and standard deviations: x1, s1, x2, and s2. (Round your answers to one decimal place.)

(b) Let μ1 be the population mean for x1 and let μ2 be the population mean for x2. Find a 99% confidence interval for μ1 − μ2. (Round your answers to one decimal place.)