Need help with daughter's Algebra 2

Discussion in 'Homeschooling' started by rose7212, Jan 21, 2011.

  1. rose7212

    rose7212 New Member

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    I hope there is someone out there who is really good with Systems of Equations. I am really stumped with this one.


    Traveling against the wind, a plane flies 2100 miles from Chicago to San Diego in 4 hours and 40 minutes. The return trip, traveling with a wind that is twice as fast, takes 4 hours. Find the rate of the plane in still air.


    A) 634.5 mi/h


    B) 637.5 mi/h


    C) 650.5 mi/h


    D) 675 mi/h


    We have to solve this problem using systems of equations. I am really confused. Usually, I can do these problems, but I cannot figure this one out.

    Thanks so much!
    Susan
     
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  3. 2littleboys

    2littleboys Moderator

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    I thought I figured it out, but I came out with 475 mi/h, so I guess I can't help you either. *shrugs*
     
  4. rose7212

    rose7212 New Member

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    Thanks for trying. I wonder if there is a problem with the answer choices. We have found problems before.

    Blessings,
    Susan
     
  5. KrisRV

    KrisRV New Member

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    Susan, Dh and daughter worked and worked on it and couldn't come up with the right answer said something was missing or its a misprint.
    They came up with the same answer 2littleboys did 475
    something was misprinted some where.
     
  6. 2littleboys

    2littleboys Moderator

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    A: 2100 mi / 4.67 hr = 449.68 mph (or 450 for argument's sake)
    B: 2100 mi / 4 hr = 525 mph

    A: 450 mph + 25 mph winds = 475 mph
    B: 525 mph - (25 x 2, or 50) mph winds = 475 mph
     
  7. rose7212

    rose7212 New Member

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    2 little boys and KrisRV,


    Thanks for explaining. That is the way that I was trying to do it, but hint said that the formulas were

    14/3 (b-c) = 2100
    4 (b+ 2c) =2100

    I did figure out that 14/3= approximately 4.68 so it is the hours
    of course the other equation is multiplied by 4 the hours again

    I still get 475, so that has to be the answer. Thanks for all the help. I feel confident that there was just an error. I guess it was just a typo. Option D should be 475 instead of 675.

    Bountiful blessings,
    Susan
     
    Last edited: Jan 22, 2011
  8. Jackie

    Jackie Active Member

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    Rachael tried, too, and couldn't figure it out.
     

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