Results 1 to 6 of 6

Math Help - Maths sum

  1. #1
    Newbie
    Joined
    Jul 2009
    From
    Maine, USA
    Posts
    9

    Maths sum

    My friend asked me this question....please help if possible:

    Sally bought some chicken wings and fishballs for a party. The cost of the chicken wings is 4/5 of the money she spent. The cost of each chicken wing to the cost of each fishball is in the ratio of 5:2. Find the ratio of the number of chicken wings to the number of fishballs Sally bought for the party.


    PS my friend and I arent 13 yet I'm sorry if its too easy


    Anna
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Jul 2009
    Posts
    397
    Hi anna

    Let:
    number of chicken wings bought = x
    number of fishballs bought = y
    total money = m
    chicken wing = cw
    fishball = fb

    Quote Originally Posted by AnnaRydell View Post
    Quote Originally Posted by AnnaRydell View Post
    The cost of the chicken wings is 4/5 of the money she spent.


    This means that : x (cw) = 4/5 m

    The cost of each chicken wing to the cost of each fishball is in the ratio of 5:2.
    This means that : 1 (cw) : 1 (fb) = 5 : 2 or
    \frac{cw}{fb} = \frac {5}{2}

    Find the ratio of the number of chicken wings to the number of fishballs Sally bought for the party.


    The question is x : y = ?

    Let's start
    x (cw) = 4/5 m ------> equation 1
    So the cost of the fishballs is 1/5 of the money. This means y (fb) = 1/5 m -------> equation 2

    Equation 1 divided by equation 2 will give you result :
    \frac{x (cw)}{y (fb)} = \frac{4/5 m}{1/5 m}

    \frac{x}{y} = \frac{4 fb}{ cw} -----> equation 3

    From the question :
    \frac{cw}{fb} = \frac {5}{2}

     cw = \frac{5}{2} fb ----> equation 4

    Subs. equation 4 to equation 3 will give you the answer ^^









    EDIT : Thx krahl ^^
    Last edited by songoku; July 31st 2009 at 09:23 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jul 2009
    Posts
    192
    Thanks
    4
    let x be # of chicken wings and y be # of fishballs

    cw is the cost of 1 chicken wing and fb is the cost of 1 fishball

    m is the amount she spent.

    then
    x(cw)=\frac{4m}{5} so  x=\frac{4m}{5(cw)}
    y(fb)=\frac{m}{5} so  y=\frac{m}{5(fb)}

    but since the cost ratio is 5:2 so i.e. 5 to 2

    2(cw)=5(fb) then  fb=\frac{2(cw)}{5}

    so

     \frac{x}{y}=\frac{\frac{4m}{5(cw)}}{\frac{m}{5(fb)  }}

     \frac{x}{y}=\frac{4(fb)}{cw}

    substituting fb=\frac{2(cw)}{5}

     \frac{x}{y}=\frac{8}{5}


    8:5

    Don't worry about asking questions which you think are too easy, this is a place where you are allowed to ask any type of question no matter how easy or hard you may think it to be.

    Songoku you may have made a mistake on equation 3 from the previous one.

    It should be \frac{x}{y}=\frac{4fb}{cw}
    Last edited by Krahl; July 31st 2009 at 09:06 PM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Jul 2009
    From
    Maine, USA
    Posts
    9
    Thanks a lot, but is it possible to do it in a simpler way? I don't really understand that method, and we seldom use algebra in school to solve questions like that.



    Anna
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Jul 2009
    Posts
    192
    Thanks
    4
    The simplest way i can think of anna is that i just decide that i have 100
    each chicken wing costs 5 and fishball costs 2.

    i find 4/5 of 100 wich is 80 and the remaining is 20

    so i know i spent 80 on cw and 20 on fb. Now lets see how many 5's goes into 80. Its 16. And 10 2's go into 20. So i know i bought 16cw's and 10fb's

    so 16:10 and rescaling, 8:5.

    Instead of starting it with 100 you could of started it with any amount you choose, its just that 100 seems like a nice round number and divisible by 5 so that's why i chose it.

    Do you understand it that way?

    (Note:I could even start with 1. but can you see what happens in this case? whenever you get a question like this all you really need to do is
    \frac{\frac{4}{5}}{5}:\frac{\frac{1}{5}}{2})
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Jul 2009
    From
    Maine, USA
    Posts
    9
    I get it now , thanks so much Krahl...!


    Anna
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Should I buy maths books to teach myself maths.
    Posted in the Math Topics Forum
    Replies: 2
    Last Post: November 21st 2011, 04:45 PM
  2. Help me with my grade 11 maths [easy maths]
    Posted in the Pre-Calculus Forum
    Replies: 11
    Last Post: December 27th 2009, 04:09 PM
  3. Maths help.
    Posted in the Algebra Forum
    Replies: 2
    Last Post: October 29th 2009, 08:17 AM
  4. Replies: 0
    Last Post: September 5th 2007, 03:50 AM
  5. Replies: 1
    Last Post: October 3rd 2006, 09:59 AM

Search Tags


/mathhelpforum @mathhelpforum