Question

Question

Question

photon336 · Answer

A recent survey of employees at a firm showed 55% drink coffee, 25% drink tea, and 35% drink neither. how many of those surveyed drink both coffee and tea?

parthkohli · Answer

So 65% people drink one of the drinks, i.e., they're in our sample space.$$\rm |tea ~\cup ~coffee| = |tea | + |coffee|-|tea ~\cap~coffee|$$$$\Rightarrow 65\% = 55\% + 25 \% - x\%$$

photon336 · Answer

Oh I get what you've done. Essentially the union of coffee and tea equals the number of people who drink coffee + the number of people who drink tea - the intersection. 
so essentially, we subtract out the intersection of coffee and tea because we don't want to double-count it? 

What's the difference between the union + intersection? the union is just total number right>  


25% tea
55% coffee 
35% neither. 

I see! 

if 35% drink neither coffee nor tea then 1-35 = 65 is the total.  

65 = 55 + 25 - 10

photon336 · Answer

OH so the union would be those who drink one or the other of those drinks not both, 

THANKS!

parthkohli · Answer

Should have mentioned "at least one", that is, their union consists of those people who drink at least one of those.

parthkohli · Answer

Anyway, yeah, hope that clears it up. I was stalking you for organic chemistry problems by the way.