September 28, 2010Math 351 - Test 11. Suppose we havefiveidenticalred books,sixidenticalgreen books, andthreedifferentyellow books.(a) In how many different ways can they be arranged on a shelf?(b) In how many different ways can they be arranged on a shelf if the yellow books must all betogether?2. Suppose we havefivedifferent math books,sevendifferent chemistry books, andfivedifferent physicsbooks. In how many ways can we selectthreebooks from each of the three subjects and then arrangethose nine selected books on a shelf in such a way that books of the same subject are kept together?3. How many ways can we dividetenidentical desks amongsixschools, assuming that not every schoolhas to be given a desk.(I suggest you begin by lettingxibe the number of desks given to schooli, whereivaries from1to 6.)4. LetAandBbe two events.Suppose in this question thatP(A) = 3/12andP(B) = 5/12.Suppose also the probability of the event that eitherAorBoccurs is7/12.
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