• Home
  • Textbooks
  • Cengage Advantage Books: Understanding Arguments: An Introduction to Informal Logic
  • Choices

Cengage Advantage Books: Understanding Arguments: An Introduction to Informal Logic

Walter Sinnott-Armstrong, Robert J. Fogelin

Chapter 12

Choices - all with Video Answers

Educators


Chapter Questions

03:00

Problem 1

Compute the probability and the expected monetary value for the following bets. Each time, you lay down $$\$ 1$$ to bet that a certain kind of card will appear from a standard fifty-two-card deck. If you win, you collect the amount indicated, so your net gain is $$\$ 1$$ less. If you lose, of course, you lose your $$\$ 1$$.

AG
Ankit Gupta
Numerade Educator
View

Problem 2

Fogelin's Palace in Border, Nevada, offers the following unusual bet. If you win, you make a 50 percent profit on your bet; if you lose, you take a 40 percent loss. That is, if you bet $$\$ 1$$ and win, then you get back $$\$ 1.50$$; if you bet $$\$ 1$$ and lose, you get back $$\$ 0.60$$. The chances of winning are fifty-fifty. This sounds like a marvelous opportunity, but there is one hitch: To play, you must let your bet ride with its winnings, or losses, for four plays. For example, with $$\$ 100$$, a four-bet sequence might look like this:
$$
\begin{array}{ccccc}
& \text { Win } & \text { Win } & \text { Lose } & \text { Win } \\
\hline \text { Total } & \$ 150 & \$ 225 & \$ 135 & \$ 202.50
\end{array}
$$
At the end of this sequence, you can pick up $$\$ 202.50$$, and thus make a $$\$ 102.50$$ profit. It seems that Fogelin's Palace is a good place to gamble, but consider the following argument on the other side. Because the chances of winning are fifty-fifty, you will, on the average, win half the time. But notice what happens in such a case:
$$
\begin{array}{lllll}
& \text { Win } & \text { Lose } & \text { Lose } & \text { Win } \\
\hline \text { Total } & \$ 150 & \$ 90 & \$ 54 & \$ 81
\end{array}
$$
So, even though you have won half the time, you have come out $\$ 19$ behind.
Surprisingly, it does not matter what order the wins and losses come in; if two are wins and two are losses, you come out behind. (You can check this.) So, because you are only going to win roughly half the time, and when you win half the time you actually lose money, it now seems to be a bad idea to gamble at Fogelin's Palace.
What should you do: gamble at Fogelin's Palace or not? Why?

Jason Gerber
Jason Gerber
Numerade Educator
02:10

Problem 3

1. Though the situation is somewhat far-fetched, suppose you are going to the drugstore to buy medicine for a friend who will die without it. You have only $$\$ 10$$-exactly what the medicine costs. Outside the drugstore a young man is playing three-card monte, a simple game in which the dealer shows you three cards, turns them over, shifts them briefly from hand to hand, and then lays them out, face down, on the top of a box. You are supposed to identify a particular card (usually the ace of spades); and, if you do, you are paid even money. You yourself are a magician and know the sleight-of-hand trick that fools most people, and you are sure that you can guess the card correctly nine times out of ten. First, what is the expected monetary value of a bet of $$\$ 10$$ ? In this context, would it be reasonable to make this bet? Why or why not?
2. Provide an example of your own where a bet can be reasonable even though the expected monetary value is unfavorable. Then provide another example where the bet is unreasonable even though the expected monetary value is favorable. Explain what makes these bets reasonable or unreasonable.

Kari Hasz
Kari Hasz
Numerade Educator