## Exercise #2

September 3, 2013

Exercise #2 is described below. **This exercise is due before class on Thu, Sep 5th.** In-class time will be allocated, time permitting, to begin the assignment on Tue, Sep 3rd.

*Please prepare your answers to the exercise questions using Microsoft Word or the equivalent and submit via email to [email protected] with the Word (.doc or .docx) file or a PDF version attached.*

Apparently people are emailing lots of different document formats to Becky, making grading cumbersome. So, instead of emailing, **please print your Excercise and turn it in at the beginning of class on Thursday** (9/5). Sorry for any confusion.

- Complete Problem 2.1 on p. 22
- Complete Problems 2.7 and 2.9 on p. 28-29
- Install the “Analysis TookPak” – see p 49 for instructions
- Use the Excel database (downloaded last week: black_7e_excel_database) to complete Analyzing the Database problems 1, 2 and 3 on p. 47-48.

**Help for problem 2.1.** I entered the data in Excel, created bins and made histograms. Hopefully this will help you understand the problem. You can use this data and the histograms for parts a and b. But, part c is up to you. Which is more useful – 5 or 10 bins? Why? Link to Excel file: Ex2_2-1

## 5 Comments

I am so confused. For problem 2.1. What would be the bin and what would be the frequency?

The bin is the same as the class interval. Take a look at the Demonstration Problem on pages 21-22 for an example. The first two columns in the Solution section display the “Interval” (or Bin) and the “Frequency”. Create one frequency distribution with 5 bins (i.e., Intervals) and one with 10 bins. The frequency distribution is simply a table displaying the interval and associated frequency, like the table on page 22 under the Solution heading. Once you’ve constructed the two tables write a few sentences to describe why you prefer 5 or 10 bins.

I uploaded an Excel file that might be helpful. Look at the new content and link to Excel file in the post above.

Another question from a student:

how do i make the frequency polygon for 2.7?For the frequency polygon you need to calculate the “Class Midpoint” for each interval and then create a line graph (preferably in Excel but a hand-drawn graph will suffice) connecting the class midpoints. You can

read about Class Midpoint on p 20-21and look at theFrequency Polygon example described on p. 25-26. Hope this helps.How do you set up the histograms for question 2.7 in excel? Using the excel analysis pack, I’m having problems trying to use the histogram function because I don’t have raw data. Unless you know of a way to get around this, I’ll most likely just use a random set of numbers that fit the criteria of the problem.

You shouldn’t need the raw data. Instead of entering “10-under-20” as the Class Interval try entering the number 10. See the example Excel file that I posted at the end of the Exercise 2 description. Let me know if you’re still confused. You can also simply draw the histogram by hand or use “Class Midpoints” for both the frequency polygon (line graph) and the histogram (bar graph).