Excel Worksheet 6–Math 243–Fall 2015

(Total: 22 points)

Instructions: Read this very carefully. In one Excel file create two sheets. Label one sheet

“Problem 1” and label the second sheet “Problem 2.” Your solutions to the two problems should

be recorded on the corresponding sheet. Additionally, you should clearly label each part of the

problems with (a), (b), etc., and every computation should be labeled. For example, in the cell

next to the mean of the data, you should have typed the word mean or average.

Be sure to do your computations using Excel. Do not do computations using Table A, Table C, or

on a calculator and then type the answers into Excel.

1. (6 points) A random digit dialing telephone survey of 880 drivers asked, “Recalling the

last ten traffic lights you drove through, how many of them were red when you entered the

intersections?” Of the 880 respondents, 171 admitted that at least one light had been red.

Give a 95% confidence interval for the proportion of all drivers who ran one or more of the

last ten red lights they met. State explicitly whether you are using a large-sample or plus

four confidence interval and why.

2. During the 2012-2013 academic year the 8% of the students at the UO spent at least one term

studying abroad. The exchange office thinks this number is on the rise. They asked a simple

random sample of 650 students whether they planned to study abroad during the 2016-2017

academic year. 60 of those students said yes.

(a) (4 points) Consider the question: Is the percent of students studying abroad going up?

Give the null and alternative hypotheses for this question in terms of the proportion of

students, p, who plan to study abroad.

(b) (4 points) Find the z test statistic.

(c) (4 points) What is the P-value for your z?

(d) (4 points) What do you conclude about the percent of students planning to study

abroad in 2016-2017?