SG #5 Word problems, Chapter 10 Medium question #18

[johnhurford]

How do you compute quantity B (the group of people who drinks neither coffee or tea)? I presume that if there's a total of 305 people and 181 drink coffee and 135 drink tea, then (181+135 - 205 = 11) 11 people drink both. So i figure that means there was no one in the survey who drinks neither? Is that correct?

[tommywallach]

Hey John,

We can't. The equation is simply:

Total = Group 1 + Group 2 - Both + Neither

305 = 181 + 135 - Both + neither
305 = 316 - Both + neither
Both - Neither = 9

At this point, we have NO idea what's what, but we know that the both group has to be bigger (to get a positive result on the subtraction).

Hope that makes sense!

-t