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Math Help - pls help!!!!!

  1. #1
    Newbie pianogurl1250's Avatar
    Joined
    Jan 2006
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    Question pls help!!!!!

    i have a question about probabilty.heres the ? theres a dartboard and the diameter is 8 in but the inner shaded circle is 4in.an it says that if i through 20 darts at it how many will land inside the shaded circle....

    theres also another one thats like this:if i drew a triangle(4ft by 1ft) on the white board(5ft by 3ft) whats the probabilty thats id hit inside the triangle if i was throwin something at it.

    PLS HELP ME I HAVE NO IDEA HOW TO DO THIS!!!!!!
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  2. #2
    Global Moderator

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    In these types of problems, you divide the area that you want to get by the area that is whole. Since the smaller circle has diameter of 4 its radius is 2 thus its area is \pi 2^2=4\pi. And the total area which is your big circle has diameter of 8 thus, radius of 4 thus, area of \pi 4^2=16\pi Now divide them thus, \frac{4\pi}{16\pi}=\frac{1}{4}. Thus probability is 25%. Since you are throwing 20 darts 20% of them should hit the region thus 20% of 20 = 5.

    Do you want to try the second one by yourself?
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