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Math Help - algebra equations

  1. #1
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    Jan 2008
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    algebra equations

    Hi

    I need help on these problems, these are practice problems for my final because the questions will be similar to these but I need help with these.
    I am lost.

    Any help would be greatly appreciated


    1) find average speed if you drive 100 miles half the trip at 60mph nd half
    30mph?

    and then
    Driving 30 minutes @ 45mph and 30 minutes @15mph



    2) of a collection of mango fruits the king took 1/6 the queen 1/5 of the
    raineder the three chief princes 1/4,1/3 and 1/2 of the successive remainders
    and the youngest child took the reamaining 3 mangoes o you who are clever in
    miscellaneous problems on fractions give out the measure of the collection of
    mangoes???


    3) I NEED TO SOLVE THIS PROBLEM BACKWARD BUT I DONT KNOW
    i began the day feeling very rich as i was walking to school i met a friend who
    had loaned me money and thought this would be a great opportunity to pay her
    back so i gave her $15 theni remembered i nedd to buy some school supplies and
    that took one third of the money in my pocket then i met another friend and she
    asked me for a loan so i gave her three fourths of the money in my pocket now i
    had only $10.00 in my pocket how much money didi i start with??


    ANY HELP WOULD BE GREATLY APPRECIATED, THANKS IN ADVANCE
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  2. #2
    Member SengNee's Avatar
    Joined
    Jan 2008
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    Pangkor Island, Perak, Malaysia.
    Posts
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    Quote Originally Posted by miramontes View Post
    1) find average speed if you drive 100 miles half the trip at 60mph nd half
    30mph?

    and then
    Driving 30 minutes @ 45mph and 30 minutes @15mph
    v_1=60
    \frac{s_1}{t_1}=60
    \frac{50}{t_1}=60
    t_1=\frac{5}{6}

    v_2=30
    \frac{s_2}{t_2}=30
    \frac{50}{t_2}=30
    t_2=\frac{5}{3}

    t=\frac{5}{6}+\frac{5}{3}=2.5

    v=\frac{s}{t}=\frac{100}{2.5}=40mph

    and then
    Driving 30 minutes @ 45mph and 30 minutes @15mph
    this means???


    Quote Originally Posted by miramontes View Post
    2) of a collection of mango fruits the king took 1/6 the queen 1/5 of the
    raineder the three chief princes 1/4,1/3 and 1/2 of the successive remainders
    and the youngest child took the reamaining 3 mangoes o you who are clever in
    miscellaneous problems on fractions give out the measure of the collection of
    mangoes???
    Let, number of mangoes is x.

    1st,
    King takes \frac{1}{6}
    Remains \frac{5}{6}

    2nd,
    Queen takes \frac{1}{5}
    Remains \frac{4}{5}

    3rd,
    The 3 chief princes take \frac{1}{4}, \frac{1}{3} and \frac{1}{2} of the successive remainders
    Remain,
    \frac{1}{2}(\frac{2}{3})(\frac{3}{4})(\frac{4}{5})  (\frac{5}{6}x)

    Last,
    The youngest child took the reamaining 3 mangoes
    Therefore,
    \frac{1}{2}(\frac{2}{3})(\frac{3}{4})(\frac{4}{5})  (\frac{5}{6}x)=3
    \frac{1}{6}x=3
    x=18



    Quote Originally Posted by miramontes View Post
    3) I NEED TO SOLVE THIS PROBLEM BACKWARD BUT I DONT KNOW
    i began the day feeling very rich as i was walking to school i met a friend who
    had loaned me money and thought this would be a great opportunity to pay her
    back so i gave her $15 theni remembered i nedd to buy some school supplies and
    that took one third of the money in my pocket then i met another friend and she
    asked me for a loan so i gave her three fourths of the money in my pocket now i
    had only $10.00 in my pocket how much money didi i start with??
    Let, your money is x.

    1st,
    You remain x-15

    2nd,
    You used \frac{1}{3}
    therefore, you remain \frac{2}{3}
    \frac{2}{3}(x-15)

    Last,
    You used \frac{3}{4}
    Therefore, you remain \frac{1}{4}
    \frac{1}{4}[\frac{2}{3}(x-15)]

    \frac{1}{4}[\frac{2}{3}(x-15)]=10
    x-15=60
    x=75
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  3. #3
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    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    thank you so much for your help, I really appreciate it


    and then
    Driving 30 minutes @ 45mph and 30 minutes @15mph
    this means???

    this means apply driving 100 miles to the question above.
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  4. #4
    Member SengNee's Avatar
    Joined
    Jan 2008
    From
    Pangkor Island, Perak, Malaysia.
    Posts
    155
    Quote Originally Posted by miramontes View Post
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    thank you so much for your help, I really appreciate it


    and then
    Driving 30 minutes @ 45mph and 30 minutes @15mph
    this means???

    this means apply driving 100 miles to the question above.
    You mean,
    1) find average speed if you drive 100 miles 30 minutes @ 45mph and 30 minutes @15mph?

    If your mean is like that, I can't solve......

    Because,

    If driving with speed 45mph for 0.5 hour,
    the distance travelled is 0.5(45)miles.

    If driving with speed 15mph for 0.5 hour,
    the distance travelled is 0.5(15)miles.

    Therefore,

    The total distance travelled is 30miles.
    I am not finish the 100miles distance.
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