Find Number of People

If there are some people, out of which 40% drink coffee, 40% drink tea, 50% drink milk, 10% drink all the three, 20% drink both coffee and tea, 20% drink both tea and milk, 20% drink both milk and coffee?

Questions by dhaval2014

Editorial / Best Answer

hydsarema  

  • Member Since Aug-2008 | Nov 25th, 2008


t=tea
c=coffee
m=milk
n=number of persons

n(c  or t or m)=n(c) +n(t) +n(m)-n(c &t)-n(t & m)- n(m & c) +n(c & t & m)

40+40+50-20-20-20+10=80

number of persons=80

Showing Answers 1 - 7 of 7 Answers

sneha36

  • Aug 29th, 2010
 

t=tea
c=coffee
m=milk
n=number of persons

n(c  or t or m)=n(c) +n(t) +n(m)-n(c &t)-n(t & m)- n(m & c) +n(c & t & m)

40+40+50-20-20-20+10=80

number of persons=80

Predhin

  • Sep 25th, 2010
 

Let t represents tea
Let c represents coffee
Let m represents milk
Let n represents number of persons

n(c U t U m)=n(c) +n(t) +n(m)-n(c &t)-n(t & m)- n(m & c) +n(c & t & m)

n=40+40+50-20-20-20+10=80

number of persons, n=80

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n(c)=40;
n(t)=40;
n(m)=40;
n(c&t)=20;
n(t&m)=20;
n(m&c)=20;
n(c&t&m)=10
so, n(c or m or t)= n(c)+n(t)+n(m)-n(c&t)-n(c&m)-n(m&t)+n(c&m&t)
                          =40+40+50-20-20-20+10
                           =80

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Sen Jacob

  • Jan 8th, 2011
 

You can also use Ven diagram for solving this kind of problems.
40%+40%+50%-20%-20%-20%+10% = 80%
So, if there is 100 people, 80 of them are drinking any of these.
How could we tell the exact number of people there?
If there is 10 people, 4drink tea, 4drink coffee, 5drink milk, 1drinks all the three. 2drink both coffee and tea, 2 drink both tea and milk, 2 drink both milk and coffee... :)
so I feel any multiple of 8 could be the answer :D
If I'm not wrong, for least case, 8 is the answer ;) (Ans: 8n - where n=1,2,3,...)
Please tell whether this helps you or not :)

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