Math 300 , Spring 2004, Day 6, F, Feb 13 Hit reload to get most current version

I am not here, but you are:
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Check all assigned problems, pool your knowledge.  I would guess that at least one person will find  Ash p. 34, # 7 less than crystal clear.  Do all you can to clarify.
Someone email me what problems you still have questions on. sievers@wells.edu
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Work as a group, or in pairs.  Choose which interests you most first.  I doubt you'll get them all.  Write up what you get and leave it in the Math 300 box outside my door.
A1)  Remember Ann and Xavier?  Suppose there are 4 girls and 3 boys, and Ann and Xavier don't want to sit next to each other.  If all are assigned at random to 7 chairs in a row, GBGBGBG, find the number of ways that A and X are NOT together?  Assuming all the children are distinguishable/ have names.  (I think assigning Xavier first is the nicest approach.)  Generalize to n boys and n+1 girls.
What is the probability that A and X are not together, if the assignment is made at random?

A2)  Now suppose there are an even number of boys and girls, still sitting alternately.  Assume BGBG...Boy first.  What are the number of ways that Ann and Xavier are not together?  (I know how to do A1; I haven't thought about A2).  Start with small numbers, see if you can generalize to n of each.  The probability they are not together?

B)  Floorcircle Suppose I have a cardboard circle whose diameter is half the length of one of the square  tiles on the classroom floor.
The experiment is to toss the circle on the floor.  What is the probability that the circle lands wholly within a square (not touching the sides)?
Assume that any place on the floor is as likely as any other place.  Hint:  Think about where the center of the circle lands, do the geometry using that.



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