Question

The local news provided poll results from 2000 adults who interview job applicants. The results showed that 35% of the adults said their biggest issue with interviewers is them not knowing company history. The margin of error was given as +/- 4 percentage points. Answer the following questions:
a. What important piece of information was omitted from the statement above?
b. What is meant by the statement that "the margin of error is +/- 4 percentage points"?
c. What are the values of?
d. If the confidence level is 95%, what is the value of?

In a poll of 555 randomly selected students, 40% stated that they enjoyed statistics. Answer the following questions:
a. Identify the number of students who say that they enjoy statistics? Round to the nearest whole student if necessary.
b. Construct a 95% confidence interval estimate of the percentage of all students who say that they enjoy statsitics.
c. Can we safely conclude that majority of students enjoy statistics? Explain.

The following information provided below shows the output from the results of performing a confidence interval for a population mean. Answer the following questions:
Confidence Interval:

(233.4, 256.65)

245.025

36.35754604

40

a. Identify the best point estimate of
b. Find the degrees of freedom.
c. Find the critical value that corresponds to n = 40.

The cholesterol levels of 40 women were sampled and a 95% confidence interval estimate was obtained below. The units of measurement for the interval below are
917.562 < < 2254.129
a. Identify the confidence interval. Include the appropriate units of measure.
b. Write a statement that correctly interprets the confidence intervale estimate of σ.

You want to estimate the mean amount of time college students spend on the Internet each month. How many college students must you survey to be 95% confident that your sample mean is within 15 minutes of the population mean? Assume that the standard deviation of the population of monthly time spent on the Internet is 210 minutes.

Answer 1

In a poll of 555 randomly selected students, 40% stated that they enjoyed statistics. Answer the following questions: a. a. Identify the number of students who say that they enjoy statistics? Round to the nearest whole student if necessary.
b. Construct a 95% confidence interval estimate of the percentage of all students who say that they enjoy statistics.
c. Can we safely conclude that majority of students enjoy statistics? Explain.

(a) It is x = 0.4 * 555 = 222

(b)

n = 555    

p = 0.4    

% = 95    

Standard Error, SE = √{p(1 - p)/n} =    √(0.4(1 - 0.4))/555 = 0.02079501

z- score = 1.959963985    

Width of the confidence interval = z * SE =     1.95996398454005 * 0.0207950097964015 = 0.04075747

Lower Limit of the confidence interval = P - width =     0.4 - 0.0407574702591045 = 0.35924253

Upper Limit of the confidence interval = P + width =     0.4 + 0.0407574702591045 = 0.44075747

The confidence interval is [0.359, 0.448], that is [35.9%, 44.8%]

(c) No, the entire confidence interval above is below 50%, so we can't conclude that majority of students enjoy statistics.

[Please give me a Thumbs Up if you are satisfied with my answer. If you are not, please comment on it, so I can edit the answer. Thanks.]