Probability

[jceriotti]

I should know this, but am stuck...question is...

Out of all the students in a biology class, exactly two of them earned a grade of 85 on the last test. There are nine girls and six boys in the class. What is the probability that two girls received a grade of 85?

We are also learning probability tree diagrams so I may set one up...but help is appreciated.

 

[tkhunny]

You really have to word questions more carefully.

If two boys earned 85%, the probability they were girls is very small. 0.00?

If two girls earned 85%, the probability they were girls is very high. 1.00?

You are drawing from a hat without replacement. Where does that go?