Suppose:
55% of adults like coffee.
25% of adults like tea.
45% of adults like cola.

and
15% drink both coffee and tea
5% drink all beverages
25% drink both coffee and cola
5% drink only tea

a) What percent of adults drink only cola?

b) What percent drink none of these beverages?

Note: This is a high school problem; question may be easily solved. Don't blame me for my ineptitude!

YianKutKu

United States142 Posts

January 08 2009 05:06 GMT

I remember doing these problems in my pre-calc class. Forgot now.

edit: use a tree diagram

Avidkeystamper

United States8556 Posts

January 08 2009 05:08 GMT

Did you try making a Venn Diagram?

Have each region represent a specific variable, and there are 7 regions non-overlapping regions, coffee, tea, cola, coffe/cola, coffe/tea, cola/tea, and coffe/cola/tea. rewrite the information given and you have a system of 7 varialbes and equations and you can just solve from there.

Also, this isn't a probability problem.

SpiritoftheTunA

United States20903 Posts

January 08 2009 05:12 GMT

45 cola - 25 coffeecola - 5 all - (25tea - 15coffeetea - 5all - 5onlytea)teacola = 15 onlycola?

100 - (15coffeetea + 5all + 25coffeecola + 5onlytea + 0teacola + 15onlycola + (55coffee - 15coffeetea - 5all - 25coffeecola)onlycoffee = 25none?

i always sucked at probability/statistics/w/e so yeah iuno mang

Fontong

United States6454 Posts

January 08 2009 05:13 GMT

^^Avidkeystamper has a clever solution, I've actually never seen this type of problem in my life despite having just taken multivariable calc(lol...). I really wouldn't know how to do it without thinking a lot.

On January 08 2009 14:06 YianKutKu wrote:
I remember doing these problems in my pre-calc class. Forgot now.

edit: use a tree diagram

You are a hunters player, yes? I think I've seen you around bnet.

Grobyc

Canada18410 Posts

January 08 2009 05:14 GMT

More effort for homework threads please.
All you did was post the problem, what do you know about the problem thus far if anything?

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:17 GMT

Make a Venn Diagram of all three. First one is pretty simple once you get it going but the second one tricked me, though I think I got it right (I took math 12 last year, and I'm in arts now so I'm not really that fresh @ this stuff), however:

Answers should be:
a)15%
b)20%

Btw you should say that 55% of adults drink coffee/tea/cola, because liking and drinking can be two different things (hope that didn't change the answer).

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:18 GMT

Do you have the answer key? can you tell us the answers? im curious now.

Peter[Deuce]

United States93 Posts

January 08 2009 05:18 GMT

Well I tried the venn diagram with 3 overlaps and each section labeled a different drink. But I got confused in the process of trying to find the answer for each question. I know about the addition rules for disjoint events like P(A) + P(B)=P(A or B).

This problem has the overlap and I honestly don't have any idea what to do.
I think it has something to do with P(A or B)=P(A) + P(B) - P(A and B)
but there's three variables so that got me pretty confused.

Peter[Deuce]

United States93 Posts

January 08 2009 05:19 GMT

#10

On January 08 2009 14:17 Resonance wrote:
Make a Venn Diagram of all three. First one is pretty simple once you get it going but the second one tricked me, though I think I got it right (I took math 12 last year, and I'm in arts now so I'm not really that fresh @ this stuff), however:

Answers should be:
a)15%
b)15%

Btw you should say that 55% of adults drink coffee/tea/cola, because liking and drinking can be two different things (hope that didn't change the answer).

Oh I just copied the problem from the book. I don't have an answer key though =[

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:23 GMT

#11

Divinek

Canada4045 Posts

January 08 2009 05:24 GMT

#12

a) 15%
b) 20%

do these add up

I have alot of pracitce with these and this was a rather easy one as long as i know how to add

il0seonpurpose

Korea (South)5638 Posts

January 08 2009 05:25 GMT

#13

I had the exact same question, ah I forgot though! Solve for coffee and tea and then the remainder should be coke.

A= Coffee
B= Tea

P(55)+ P(25)-P(15)= 55

So the remaining should be 45% who like coke

Actually I'm not sure if that's right but I think .45 is one of the answers

Edit: NVM, look at the diagram above ^^^^^^

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:27 GMT

#14

That sucks no answers how are you supposed to know your doing a question right.

SpiritoftheTunA

United States20903 Posts

January 08 2009 05:28 GMT

#15

yeah they do divinek, i just realized the mistake in mine was that i assumed the phrase "coffee and tea" meant "coffee, tea, but not cola" and etc etc etc so it led to me calculating that tea+cola and not coffee was 0

i dunno man honestly it could go both ways

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:29 GMT

#16

Fucking hell everybody has different answers, I am going to do this again.

Peter[Deuce]

United States93 Posts

January 08 2009 05:30 GMT

#17

Ah I get the first, still wondering what I subtract to get the second.

Yeah my teacher gave me an even problem; I don't know why. The second answer seems right. Thanks. I never liked venn diagrams =/

Zapdos_Smithh

Canada2620 Posts

January 08 2009 05:30 GMT

#18

yeah I made another mistake Divinek has it right.

Divinek

Canada4045 Posts

January 08 2009 05:30 GMT

#19

On January 08 2009 14:27 Resonance wrote:
No answer? Man that's a bad teaching method how are you supposed to know if what you are doing is right?

Anyway here is my logic for both of your questions:

For the first one it's pretty simple, just find the only Cola drinkers %.

For the second, what I did was get all the percentages (after broken down, 15+25+5+15+5+10+0=75)

Then just go 100% - 75 = 25...rofl yeah ok so I made that mistake there I'm really fucking tired haha

So answers are 15% and 25%

When you get to 3rd/4th year math courses atleast none of the books have answers, at all.

It's suprising how many people got this wrong. Pictures really do help, always, always, always.

SpiritoftheTunA

United States20903 Posts

January 08 2009 05:31 GMT

#20

On January 08 2009 14:30 Divinek wrote:

Show nested quote +

When you get to 3rd/4th year math courses atleast none of the books have answers, at all.

It's suprising how many people got this wrong. Pictures really do help, always, always, always.

it was a semantics issue, my method was perfectly fine if in the OP the phrases like "cola and coffee" meant exclusive of tea