Difference between revisions of "HW 2:" - Rhea

Revision as of 11:53, 27 January 2010

Can anyone tell me how to start #61? Maybe I'm just missin something, but I can't figure it out.

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Can anyone tell me how to go about doing problem 14?

Can someone help me with #20d. Does it mean a positive integer under 1000 that is divisible by only the numbers 7 and 11? ^***YES***

It means the set containing numbers divisible by 7 union the set containing the numbers divisible by 11

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Can anybody help me out with 30h. Does the book mean only starts OR ends with BO or does it include the one the starts with AND ends with BO?

It wants to know starts OR ends with BO. Think of the equation for union for this problem. That being, # that start with BO + # that end with BO - # that start and end with BO.

I need some help with 44. Anyone know how to do it?

For 30h, "or" always means union

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For 44, 1)there are 6 different consecutive positions. 2)on those consecutive positions there could be 1 or 0. 3)there are 2^5 ways to fill other positions. 4)then combine the above ideas together, and it is over to you

Thanks for the help on 44. It really helped me out and now i understand how to get it.

In regards to the steps above for 44: depending on how you implement those ideas, be very careful of over count.

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anyone have any ideas on how to go about 7.5 #14???

For 14, try thinking of both letters and words as distinct objects that can be ordered.

Can anyone help with 20e. Number 40c is like it. Whats it asking for when it wants EXACTLY ONE of something?