Probability problem.

May 2010
37
0
How would I find the answer to...
In a class with 50 students, 25 of the students are female, 15 of the sudents are mathematics majors, and 10 of the mathematics majors are female. If a student in the class is to be selected at random, what is the probability that the student selected will be female or a mathematics major or both?
 
May 2010
3
0
Pr[X is female or X is maths major or x is female and maths major]
=Pr[X is female or X is maths major]
=Pr[X is female] + Pr[X is maths major] - Pr[X is female and maths major]
=25/50 + 15/50 - 10/50
=30/50
 

Soroban

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May 2006
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Lexington, MA (USA)
Hello, dnntau!

In a class with 50 students, 25 of the students are female,
15 of the students are math majors, and 10 of the math majors are female.

If a student in the class is to be selected at random, what is the probability
that the student selected will be female or a mathematics major or both?

You can draw a Venn diagram or put the data into a chart . . .


. . \(\displaystyle \begin{array}{c||c|c||c|}
& \text{Math} & \text{Other} & \text{Total} \\ \hline \hline
\text{Female} & 10 & & 25 \\ \hline
\text{Male} & & & 25 \\ \hline \hline
\text{Total} & 15 & 35 & 50 \end{array}\)


Fill in the empty cells and answer the question.