A student studying for a vocabulary test knows the meanings of 10 words from a list of 20 words. If the test contains 10 words from the study list, what is the probability that at least 8 of the words on the test are words that the student knows? (Round your answer to three decimal places.)

Question

anonymous · Answer

1/2 * 9/19 * 4/9*7/17 * 3/8 * 1/3 * 2/7 *3/13
multiply all those fractions:

anonymous · Answer

thats not right.

anonymous · Answer

So this looks like a set/stats problem. So first you have to figure out 20 choose 10, which will be the total number of possible sets of ten test questions. Then you have to figure out the probability of there being 8, or 9, or 10 words he knows on the test. There is a formula for this in whatever stats/probability text book your using (I'm guessing you're in such a class judging on the kind of questions you're asking).