# Homework Help: Probabilities of this marketing department information

1. Nov 30, 2009

### Draggu

1. The problem statement, all variables and given/known data

The marketing department of a magazine collects the following information for a group of randomly selected subscribers. Of households that subscribe to at least one of their three magazines:
25 subscribe to teen world only
19 to star watch only
15 to fashionz only
41 to teen world and star watch
28 to star watch and fashionz
32 to teen world and fashionz
11 to all three magazines
a) Illustrate with a venn diagram

b) Determine the probability that a randomly selected subscriber receives
i) all three magazines
ii) exactly two magazines
ii) at least two magazines
iv) Fashionz
v) star watch or teen world

2. Relevant equations

3. The attempt at a solution

b)

i) N(A)=11
N(S)=138

P(A)=11/138

ii) 21+17+30/138=34/69

iii) 21+17+30+11/138 = 79/139

iv) 15/138
v)

2. Nov 30, 2009

### Draggu

Re: Probabilities

Here is the venn diagram btw.

http://i48.tinypic.com/2k4pdz.jpg

3. Dec 2, 2009

### Cryphonus

Re: Probabilities

Please follow the plan that is introduced as the first topic of this section, i assume you didnt understand v part?? If you can clarify tha part that you didnt understand i can help you in a better way.

For the v part) (taking reference of your venn diagram in the link) 30 people is subscribed to both teen and and star,19 is subscribed to only star and 25 for the teen.So the probabilty of chosing someone that is subscribed to "teen or star" is:

19 plus 30 plus 25 over total number of people.

4. Dec 2, 2009

### willem2

Re: Probabilities

for iii) you should have 79/138 instead of 79/139 (probably a typo)
for iv) the question was not "who subscribes only to fashionz" but "who subscribes to fashionz, any other subscribtions or the lack thereof are irrelevant"