Question

1. A store randomly samples 603 shoppers over the course of a year and finds that 142 of them made their visit because of a coupon they'd received in the mail.

   A 95% confidence interval for the fraction of all shoppers during the year whose visit was because of a coupon they'd received in the mail is (0.2016, 0.2694)

   The store management can be 95% confident that any sample of shoppers would have a proportion of visitors whose visit is because of receiving a coupon be within this confidence interval

   The store management can be 95% confident that the population proportion of customers visiting the store because they received a coupon is within our confidence interval

   95% of customers visiting the store because of receiving a coupon is within our confidence interval

QUESTION 4

1. Workers at a particular mining site receive an average of 35 days paid vacation, which is lower than the national average. The manager of this plant is under pressure from a local union to increase the amount of paid time off. However, he does not want to give more days off to the workers because that would be costly. Instead he decides he should fire 10 employees in such a way as to raise the average number of days off that are reported by his employees. In order to achieve this goal, should he fire employees who have the most number of days off, least number of days off, or those who have about the average number of days off?

   a.

   He should file employees who have the most number of days off.

   b.

   No matter who he fires, it will not increase the amount of paid time off.

   c.

   He should file employees who have the average number of days off.

   d.

   He should file employees who have the least number of days off.

1. Suppose the observational units in a study are the patients arriving at an emergency room on a given day, 11 Nov 2019. For the following indicate whether it can legitimately be considered a variable or not:

   Whether or not men have to wait longer than women

   yes

   no

QUESTION 8

1. A survey company published results of a survey stating that 56% of the 600 randomly sampled residents planned to set off firereworks on July 4th.

   Determine the margin of error for the 56% point estimate using a 95% confidence level.

   Give your answer as a decimal rounded to two decimal places. (like .02 or .07 or .12)

1. SAT scores (out of 2400) are distributed normally with a mean of 1480 and a standard deviation of 320. Suppose a school council awards a certificate of excellence to all students who score at least 1900 on the SAT, and suppose we pick a student at random. What is the chance they will have a score at least 1900?

   (Give your answer in decimal form to 4 places, like .0304 or .1421)

Answer 1

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Answer:

1)

The store management can be 95% confident that the population proportion of customers visiting the store because they received a coupon is within our confidence interval.

From the confidence interval, it is clear that one can be 95% confident that the true proportion of shoppers made their visits because of a coupon they’d received in the mail is between 0.2016 and 0.2694.

2)

He should file employees who have the least number of days off.

As the average days rises when we fire the employees with most days off

3)

Whether or not men have to wait longer than women

Binary variable, Yes

4)