"When you can measure what you are talking about and express it in numbers, you know something about it." -- (Lord Kelvin, 1824-1907) Henry Wadsworth Longfellow (1807-1882): He was an accomplished mathematician who created problems in poetic settings. He resigned his position of modern languages at Harvard University to find time to write - and his writing included some mathematics, a subject for which he had a deep appreciation. Can you find the number of water lilies in this problem created by Longfellow? One-third of a collection of beautiful water lilies is offered to Mahadev, one-fifth to Huri, one-sixth to the Sun, one-fourth to Devi, and six which remain are presented to the spiritual teacher. When Herkimer was a waiter, what did he say to a customer who ordered a lobster tail? Answer: "Once upon a time there was a handsome lobster who ... " Things Herky would like to know: If 7-11 is open 24 hours a day, why are there locks on the doors? Is it true that cannibals don't eat clowns because they taste funny? ASSIGNMENT #36 Reading: Section 6.2 (pages 324-329). Exercises: 6.18 - 6.23 (pages 330-331). You can write answers neatly in the text.

You are in Section 6.2.

The probability rules stated on page 325 arepretty much good old common sense. Do note that Rule #4 is true onlyif the events A and B are disjoint. Consider rolling twodice and noting the sum on the up faces. Events A and B are definedas follows:

A: Obtaining a total of 7. Prob (A) =6/36.
B: Obtaining a total of 9. Prob (B) = 4/36.

In this situation, A and B are disjoint events.That is, they cannot occur simultaneously. Hence

Prob (A or B) = 6/36 + 4/36 =10/36.

Now define events C and D as follows:

C: Obtaining a total less than 5. Prob(C) = 6/36.

D: Both up faces show a 2. Prob (D) = 1/36.

In this case, C and D are not disjoint since theycan occur simultaneously. That is, if both faces show a 2, then youhave a total of 4, which is less than 5. In this situation, event Cactually includes event D, and we have Prob (C or D) = 6/36, which isnot Prob (C) + Prob (D).

=======================================

Text:
The Practice of Statistics, by Yates, Moore, McCabe. New York,W.H. Freeman and Company, 1999. (ISBN 0-7167-3370-6)

Supplemental books:
The Cartoon Guide to Statistics, by Gonick and Smith. NewYork, HarperCollins Publishers, 1993. (ISBN 0-06-273102-5)
How to Lie with Statistics, by Darrell Huff. New York, W.W.Norton & Company, 1982 (ISBN 0-393-09426-X)