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Thread: Any math geniuses care to help me?

  1. #1
    Kaylinn
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    Default Any math geniuses care to help me?

    I'm completly math stupid. My math professor is a total idiot and I'm not learnign anything. I have 2 math problems I don't know how to solve.
    Can anyone help?
    Here are the problems:

    #1
    1/r=210/1050+70/1050+30/1050+21/1050
    Which would mean
    1/r=331/1050
    right?
    But now what?

    #2
    9.717 * 18 to the 8th power * 5.78 * 10 to the 12th power /1 lightyear * 1km/0.612mi

    The exact problem states A distant star is 9.717 *10 to the 8th light years away from earth. If 1 light year is 5.87*10 to the 12th miles, how many kilometers is the star from earth? Report answer in standard form. Use 1km=0.6214mi.
    I think I set up the problem right, but I just don't know how to work eitherr of them.

    Can anyone help please?

  2. #2
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by Kaylinn View Post
    I'm completly math stupid. My math professor is a total idiot and I'm not learnign anything. I have 2 math problems I don't know how to solve.
    Can anyone help?
    Here are the problems:

    #1
    1/r=210/1050+70/1050+30/1050+21/1050
    Which would mean
    1/r=331/1050
    right?
    But now what?
    Now cross-multiply both sides to isolate remove denominators and get:
    1050 = 331r
    Divide by 331 to isolate r:
    1050/331 = r

    I have to look at the second one a little more.



    Because there ain't no tits on the radio

  3. #3
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by Kaylinn View Post
    #2
    9.717 * 18 to the 8th power * 5.78 * 10 to the 12th power /1 lightyear * 1km/0.612mi

    The exact problem states A distant star is 9.717 *10 to the 8th light years away from earth. If 1 light year is 5.87*10 to the 12th miles, how many kilometers is the star from earth? Report answer in standard form. Use 1km=0.6214mi.
    I think I set up the problem right, but I just don't know how to work either of them.

    Can anyone help please?
    Try
    [9.717*10^8(5.87*10^12)]/.612

    I think. It's been awhile since I've had a real math class.



    Because there ain't no tits on the radio

  4. #4
    Kaylinn
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by hardkandee View Post
    Now cross-multiply both sides to isolate remove denominators and get:
    1050 = 331r
    Divide by 331 to isolate r:
    1050/331 = r

    I have to look at the second one a little more.
    That's what I thought, I just wasn't sure.

    Thanks.

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    Default Re: Any math geniuses care to help me?

    The answers given are correct.

  6. #6
    Kaylinn
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by hardkandee View Post
    Now cross-multiply both sides to isolate remove denominators and get:
    1050 = 331r
    Divide by 331 to isolate r:
    1050/331 = r

    I have to look at the second one a little more.
    r = 3172x 10^3

    Correct?

  7. #7
    God/dess Bob_Loblaw's Avatar
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    Default Re: Any math geniuses care to help me?

    ?!? Granted, I'm drunk right now but this is what I get...

    1/R=210/1050+70/1050+30/1050+21/1050
    1/R=(210+70+30+21)/1050
    1/R=331/1050
    (1*1050)=(331*R)
    (1*1050)/331=(331*R)/331
    1050/331=R

    Yup, same as hardkandee

  8. #8
    Kaylinn
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    Default Re: Any math geniuses care to help me?

    I just used the coolest live online tutoring chat thingy.
    I hope the totor helped me get to the right answers.

    Thank you guys so much for your help!

  9. #9
    God/dess Bob_Loblaw's Avatar
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by Kaylinn View Post
    #2
    The exact problem states A distant star is 9.717 *10 to the 8th light years away from earth. If 1 light year is 5.87*10 to the 12th miles, how many kilometers is the star from earth? Report answer in standard form. Use 1km=0.6214mi.
    I'm probably wrong but I work it this way:

    ((9.717*10^8 )/1)*((5.87*10^12)/0.6214)) = x
    (0.6214*9.717*10^8 )*(5.87*10^12) = 0.6214x
    9.717*5.87*10^20 = x
    x = 57.03879*10^20
    x = 5,703,879,000,000,000,000,000KM

    Don't listen to me. I didn't have my abacus handy.

  10. #10
    Kaylinn
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    Default Re: Any math geniuses care to help me?

    ^ That is not what I got.
    My final answer( with the help of the tutor) was 9183440000000000000000km

    I'm not sure if it's right..the tutor didn't seem to be all that good. He kept forgetting numbers, and I'd have to remind him.

  11. #11
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    Default Re: Any math geniuses care to help me?

    Bob you forgot to divide by .6214

    Problem two you are doing dimensional analasys.

    You want to convert ly to km by way of miles.

    ly*(mi/ly)*(km/mi)

    so you set the proble up:

    (9.717x10^8ly)*((5.87x10^12mi)/(1ly))*((1km)/(.6214mi))
    (9.717x10^8*5.87x10^12/.6214)km
    9179077888638558094625.0402317348km
    or 9.18x10^21km because you only have 2 signifigant figures in your ly to miles conversion

  12. #12
    Kaylinn
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    Default Re: Any math geniuses care to help me?

    well, wait.
    That's the 3rd different answer.
    fuck.

    I'm so confused.

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    God/dess britneyireland's Avatar
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    Default Re: Any math geniuses care to help me?

    #1 r=3.17

    haven't started 2
    Rebecca Avalon







  14. #14
    God/dess Bob_Loblaw's Avatar
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    Default Re: Any math geniuses care to help me?

    I'm drunk so I have an excuse. Actually, it's no excuse but I'm running with it.

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    Featured Member lizlizliz's Avatar
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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by Bob_Loblaw View Post
    I'm probably wrong but I work it this way:

    ((9.717*10^8 )/1)*((5.87*10^12)/0.6214)) = x
    (0.6214*9.717*10^8 )*(5.87*10^12) = 0.6214x
    9.717*5.87*10^20 = x
    x = 57.03879*10^20
    x = 5,703,879,000,000,000,000,000KM

    Don't listen to me. I didn't have my abacus handy.
    hehe, you said abacus. that's in my top 5 all-time fav words.

    thank you ultima vii: serpent isle

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    Default Re: Any math geniuses care to help me?

    Quote Originally Posted by Kaylinn View Post
    I'm completly math stupid. My math professor is a total idiot and I'm not learnign anything. I have 2 math problems I don't know how to solve.
    Can anyone help?
    Here are the problems:

    #1
    1/r=210/1050+70/1050+30/1050+21/1050
    Which would mean
    1/r=331/1050
    right?
    But now what?

    #2
    9.717 * 18 to the 8th power * 5.78 * 10 to the 12th power /1 lightyear * 1km/0.612mi

    The exact problem states A distant star is 9.717 *10 to the 8th light years away from earth. If 1 light year is 5.87*10 to the 12th miles, how many kilometers is the star from earth? Report answer in standard form. Use 1km=0.6214mi.
    I think I set up the problem right, but I just don't know how to work eitherr of them.

    Can anyone help please?
    (9.717 x 10^8 light years ) x (5.87 x 10^12 miles / 1 light year) x (1 km / .6214 mile) = 9.179 x 10 ^ 21 kilometers which i assume is standard form. If you follow the units the only unit left is the km on the top.
    Last edited by space_Cadet_28; 10-18-2007 at 07:31 AM.

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