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June 16th, 2013, 09:26 PM   #1
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Probability

The probability of the students studying in Science is 30, and in Commerce is 45, and there are 10 students who study both, find the total number of students in the class ?
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June 17th, 2013, 05:58 AM   #2
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Re: Probability

Where did you get this problem? You titled this "Probability" but surely if you were taking a probability class you would understand that a "probability" is always between 0 and 1. "The probability of the students studying in Science is 30" is impossible. I suspect that the problem says that there are 30 students studying Science. If there are 45 studying Commerce, do you see why "the number who are studying both" is not just 30+ 45? It is because, that way, you are counting the 10 students who are studying both.

If there are 30 students studying Science and 10 of those are also studying Commerce, how many are studying Science only?
If there are 45 students studying Commerce and 10 of those are also studying Science, how many are studying Commerce only?

Now, can you answer the question?
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