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probability

by [email protected] » Wed Jun 30, 2010 9:12 pm
A dance instructor conducts annual workshops in which he holds sessions for basic learners and trainers. In a particular year, 2000 people attended the workshop. 1500 participated as learners and 800 as trainers. How many participated as only trainers?
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by selango » Wed Jun 30, 2010 9:27 pm
Total=2000

P(L)=1500

P(T)=800

Total=P(L)+P(T)-P(LnT)

2000=2300-P(LnT)

P(LnT)=300

P(T)=P(T)-P(LnT)

=800-300

=500
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by 4GMAT_Mumbai » Wed Jun 30, 2010 9:28 pm
Hi,

Probability ???? Ain't it Set theory ?!?!?

n (A) = 1500

n (B) = 800

n (A union B) = 2000

n (A union B) = n(A) + n(B) - n(A intersection B)

2000 = 1500 + 800 - x

Hence, x = 300. i.e., 300 ppl were both trainers and learners.

Hence, only trainers = [spoiler]800 - 300 = 500[/spoiler].

Hope this helps. Thanks.
Naveenan Ramachandran
4GMAT, Dadar(W) & Ghatkopar(W), Mumbai
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by selango » Wed Jun 30, 2010 9:32 pm
bubblyrathi,

All the problems u posted now are set theory problems.It can be solved using Venn Diagrams.
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