a list contains the names of 5 anthropology students, 2 sociology students, and 3 psychology students. If a name is selected at random to assist in th

A list contains the names of 5 anthropology students, 2 sociology students, and 3 psychology students. If a name is selected at random to assist in the professors new study. Find the probability that the chosen student is (a) an anthropology student, (b) a psychology student, (c) an anthropology student or a sociology student, (d) not a psychology or a sociology student.
 
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The problem that you have posted is unanswerable. Presumably, additional information is available in the problem. Please write the problem completely and exactly and show what you have tried even if you are certain it is wrong so we can see where and how to help.
 
lawkid said:
A list contains the names of 5 anthropology students, 2 sociology students, and 3 psychology students. If a name is selected at random to assist in the professors new study. Find the probability that the chosen student is (a) an anthropology student, (b) a psychology student, (c) an anthropology student or a sociology student, (d) not a psychology or a sociology student.
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I added the visible part of the subject-line.
 
Do you know anything at all about probability? If this is a problem you were given in a class you certainly should! For example, you should have learned, as a basic definition of probability, that if a box contains m red balls and n yellow balls and I draw one at random, the probability it is red is m/(m+n) and the probability it is yellow is n/(m+n). That is all you need to know to do this problem.

How many students are you choosing from, all together?

How many of those students are anthropology students? How many are psychology students? How many are anthropology students or sociology students? How many are NOT psychology or sociology students?
 
HallsofIvy said:
Do you know anything at all about probability? If this is a problem you were given in a class you certainly should! For example, you should have learned, as a basic definition of probability, that if a box contains m red balls and n yellow balls and I draw one at random, the probability it is red is m/(m+n) and the probability it is yellow is n/(m+n). That is all you need to know to do this problem.

How many students are you choosing from, all together?

How many of those students are anthropology students? How many are psychology students? How many are anthropology students or sociology students? How many are NOT psychology or sociology students?
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Actually, we do not know how many students are on the list so calculating probabilities is impossible. Of course, it is possible that the student did not paraphrase the problem particularly well.
 
JeffM said:
Actually, we do not know how many students are on the list so calculating probabilities is impossible. Of course, it is possible that the student did not paraphrase the problem particularly well.
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Why do we not? The original statement said
"A list contains the names of 5 anthropology students, 2 sociology students, and 3 psychology students."

I see no reason to assume that is not the entire list.
 
HallsofIvy said:
Why do we not? The original statement said
"A list contains the names of 5 anthropology students, 2 sociology students, and 3 psychology students."

I see no reason to assume that is not the entire list.
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I do. There is an important distinction between the meaning of "contain" and of "consist."

"The zoo contains tigers and flamingoes" does not preclude elephants from being in the zoo.

Word problems are the key to learning how to apply mathematics. Students should not have to guess at what the words are intended to mean. Was the problem badly phrased, in which case the student has a right to be confused? Or was the problem correctly phrased but badly paraphrased, in which case the student is already on the road to confusion?
 
That's a very good point but given that, the problem becomes Impossible to solve. I could see noting that in your answer but then proceeding to solve the problem with the assumption that these are the only people involved.
 
HallsofIvy said:
That's a very good point but given that, the problem becomes Impossible to solve. I could see noting that in your answer but then proceeding to solve the problem with the assumption that these are the only people involved.
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I completely take your point, but I really was trying to get the student to indicate some thought process. Students who simply state a problem without indicating any thought need a (virtual, non-physically harmful) shake. Mine was perhaps too subtle. (I also get annoyed at word problems that are badly worded. Mathematicians know, and should remember, how important is careful delineation of a problem.)
 
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