Word Problems Guide 5 Chapter 7 Problem Set 6 2nd Ed.

[ryandonahue]

Having issues with:
Word Problems Guide 5 Chapter 7 Problem Set 6 2nd Ed.

6.John Invites 12 Friends to a dinner party, half of which are men. Exactly one man and one woman are bringing deserts. I f one person form this group is selected at random, what is the probability that it is a woman, or man who did not bring a dessert?

I'm just not fully understanding the explanation given in the answers and help and insight is very much appreciated.

Thanks
Ryan

[jen]

No problem. Here are the 12 people:

man1
man2
man3
man4
man5
MAN6 WITH DESSERT
woman1
woman2
woman3
woman4
woman5
WOMAN6 WITH DESSERT

If we pick 1 person, the probability of getting a woman or a man who is not bringing dessert will equal

the total number of people fulfilling the requirements
____________________
the total number of people

Since there are six women (we don't care whether they have dessert) and five men (with no dessert), the answer is

11/12

The explanation in the book also shows another way to do it:
The probability of picking a woman is 6/12.
The probability of picking a man with no dessert is 5/12.

Since this is an OR question (we'll only be picking one person, so we could not pick BOTH a woman and a man with no dessert), add 6/12 and 5/12 to get 11/12.

Jen

[ryandonahue]

Thanks Jen.

Again a fantastic explanation to attack this problem! I'm not sure why I wasn't following the guides explanation very well but yours really helps.


Thanks again
Ryan

[tommywallach]

Hey Ryan,

Glad Jen could help! Feel free to post more questions as they come up!

-t

(I'm just posting this so I can see that this is topic is, for now, closed out.)