BrownMath.com → Statistics → Sum15 ME58 → Probability Lab
Updated 25 May 2015

Probability Lab (Due on 24 Jun)

portions Copyright © 2014–2015 by Stan Brown

Data Collection

Use the data sheet at the end of this lab, or separate paper laid out the same way. Pick any 29 TC3 students, some men and some women, some who live on campus and some who don’t. Ask the questions, and fill in the values of the following categorical variables for each student:

Add yourself as the 30th person.

Directions for This Lab

Two-Way Tables

Question 1 (9 points):  Make three two-way tables to summarize the data:

On
Campus
Off
Campus
Evening|||| |||||| |
No Evening|||||||| |||| ||
On
Campus
Off
Campus
Total
Evening7613
No Evening51217
Total121830

For each two-way table, go once through your raw data and put a tally mark in the appropriate box for each student, like the table at left above. Then count the tallies to make a final table like the one at right. Fill in row and column totals, and verify that the totals add each way to your sample size of 30.

For some tables, you will need more than two rows or columns.

Data Analysis

Question 2 (18 points):  Assume that your data are representative of TC3 students in general. Find each probability below, and interpret it in an English sentence.

Example: P(Evening).
Answer: P(Evening) = 13/30 or about 43%. There’s a 43% chance that any randomly selected student takes evening classes. [Equally acceptable: 43% of students take evening classes.]

Use your own data for the rest of these, and remember to show your computations.

(a) P(male)
(b) P(lives on campus)
(c) P(comedyC) — I didn’t mean P(comedy).
(d) P(female and blue eyes)
(e) P(evening class or lives on campus)
(f) P(male or prefers horror/thriller)
(g) P(evening class | lives off campus)
(h) P(female and prefers comedies)
(i) P(brown eyes | male)

Question 3 (3 points):  According to your sample, not what you may know or think about students in general, is prefers romance movies mutually exclusive with male? Explain.

Question 4 (3 extra-credit points):  According to your sample, not what you may know or think about students in general, are lives on campus and takes evening classes independent events? Explain.

Acknowledgement

This lab was adapted from an assignment created by Benjamin Kirk for his classes, and is used with his kind permission.

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