# Mat 510 homework assignment 9 quiz

Question 1

1. Homework Assignment 9

Due in week 10 and worth 30 points

Suppose that there are two (2) candidates (i.e., Jones and Johns) in the upcoming presidential election.  Sara notes that she has discussed the presidential election candidates with 40 friends, and 27 said that they are voting for candidate Jones. Sara is therefore convinced that candidate Jones will win the election because Jones gets more than 50% of votes.

Answer the following questions in the space provided below:

1. Based on what you now know about statistical inference, is Sara’s conclusion a logical conclusion? Why or why not. What inference test should she use?

Yes because more   than 50% of her friends are voting for Jones and thus she has enough   evidence. She needs to conduct a two-proportion z-test.

No because she must   check that her sample size meets the sufficient conditions for a   one-proportion test. She also has to determine if her sample size is large   enough. She should conduct a one-proportion z-test.

5 points

Question 2

1. Homework Assignment 9

Due in week 10 and worth 30 points

Suppose that there are two (2) candidates (i.e., Jones and Johns) in the upcoming presidential election.  Sara notes that she has discussed the presidential election candidates with 40 friends, and 27 said that they are voting for candidate Jones. Sara is therefore convinced that candidate Jones will win the election because Jones gets more than 50% of votes.

2. What z-score did she obtain?

Z=2.21

Z=221

Z=2.21%

Z=.221

5 points

Question 3

1. What should her conclusion state?

Given p   = 0.014 and alpha is 0.025 given a two-tail test we FRN.

Given   p = 0.05 and alpha is 0.014 given a one-tail test we RN.

Given   p = 0.014 and alpha is 0.025 given a one-tail test we   FRN.

Given   p = 0.014 and alpha is 0.05 given a one-tail test we RN.

5 points

Question 4

1. Compute the 95% confidence      interval.

The 95% confidence   interval is between 53% and 82%.

There is   insufficient evidence that this confidence interval has meaning.

(.513, .831)

(.675, .98)

5 points

Question 5

1. What role does the margin of error play in determining how many individuals should be sampled if we desired a margin of error plus or minus .000001?

Not much since we   did not meet the criteria for conducting a confidence interval.

Such a small margin   means we are very close to accurately predicting the winner.

Less error means a   wider confidence margin.

The margin of error   is a really good butter to use when cooking.

5 points

Question 6

1. How would you explain your conclusion to Sara without using any statistical jargon? In other words, is her original sample size sufficient or should she interview more people to obtain an accurate prediction.

Simply stated, the   number of friends selected may be indicative that you are surrounded by like   minded people and does not necessarily reflect the opinion of the greater   population.

Simply   stated, the number of friends selected may be indicative that you are   surrounded by like minded people and does reflect the opinion of the greater   population.

Simply   stated, the sample size is too large.

The sample size   does not matter. Jones will win because your friends think he will win.