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Math Help - Supply and demand function?

  1. #1
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    Supply and demand function?

    Let S and D be the supply and demand functions, respectively, for a particular item; also let these be functions of price as follows: S(p)= -1000 + 2500p, D(p)=9000 - 2000p. The equilibrium price is that price at which supply and demand (S=D).

    (a). Find the equilibrium price p.
    (b). Find the equilibrium price quantity, S or D.
    (c). Determine the prices for which quantity demanded is less than quantity supplied.

    Here's what I got:

    -1000 + 2500p = 9000 - 2000p
    4500p=10000
    p= 2.22222 (repeating)

    So I put in 2.2 for S and got 4500 and then 2.2 for D and got 4600. Shouldn't they be the same?

    I'm confused as to what to do next
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  2. #2
    Bar0n janvdl's Avatar
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    Quote Originally Posted by romanianxromo View Post
    Let S and D be the supply and demand functions, respectively, for a particular item; also let these be functions of price as follows: S(p)= -1000 + 2500p, D(p)=9000 - 2000p. The equilibrium price is that price at which supply and demand (S=D).

    (a). Find the equilibrium price p.
    (b). Find the equilibrium price quantity, S or D.
    (c). Determine the prices for which quantity demanded is less than quantity supplied.

    Here's what I got:

    -1000 + 2500p = 9000 - 2000p
    4500p=10000
    p= 2.22222 (repeating)

    So I put in 2.2 for S and got 4500 and then 2.2 for D and got 4600. Shouldn't they be the same?

    I'm confused as to what to do next
    Set p = \frac{20}{9} = 2,22222.....

    S = D = 4555,55555....
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  3. #3
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    Quote Originally Posted by janvdl View Post
    Set p = \frac{20}{9} = 2,22222.....

    S = D = 4555,55555....
    Where did you get the 20 from?

    Then how would I find the prices for which quantity demanded is less than the quantity supplied?
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  4. #4
    Bar0n janvdl's Avatar
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    Quote Originally Posted by romanianxromo View Post
    Where did you get the 20 from?

    Then how would I find the prices for which quantity demanded is less than the quantity supplied?
     2,2222.... = \frac{20}{9}

    The reason yours is wrong is because you rounded.

    Do NOT round until your final answer for the question.
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    So then the price for the quantity demanded is less than the quantity supplied

    is that 455,555....?

    Or is it something else?
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  6. #6
    Bar0n janvdl's Avatar
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    Quote Originally Posted by romanianxromo View Post
    So then the price for the quantity demanded is less than the quantity supplied

    is that 455,555....?

    Or is it something else?
    Price is equal for quantity demanded and supplied since the market has reached equilibrium.

    4 555,55.... will be the quantities.
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  7. #7
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    ur question is not correct

    qd = 9000-2000p
    qs = -1000 + 2000p

    qd =qs

    -1000 + 2500p = 9000-2000p
    collect like terms

    10000 = 500p
    p= 10000/500 = 100/5 = 20
    equilibrium price is N20.

    qs = -1000 + 2500(20)
    = -1000 + 50000
    = 49000
    qd = 9000-2000(20)

    = 9000 - 40000
    = - 31000
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  8. #8
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    Quote Originally Posted by cokhale View Post
    qd = 9000-2000p
    qs = -1000 + 2000p

    qd =qs

    -1000 + 2500p = 9000-2000p
    collect like terms

    10000 = 500p
    p= 10000/500 = 100/5 = 20
    equilibrium price is N20.

    qs = -1000 + 2500(20)
    = -1000 + 50000
    = 49000
    qd = 9000-2000(20)

    = 9000 - 40000
    = - 31000
    Where are you getting the 500p from? When you add 2000p, you get 4500, not 500
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  9. #9
    Bar0n janvdl's Avatar
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    Quote Originally Posted by cokhale View Post
    qd = 9000-2000p
    qs = -1000 + 2000p

    qd =qs

    -1000 + 2500p = 9000-2000p
    collect like terms

    10000 = 500p
    p= 10000/500 = 100/5 = 20
    equilibrium price is N20.

    qs = -1000 + 2500(20)
    = -1000 + 50000
    = 49000
    qd = 9000-2000(20)

    = 9000 - 40000
    = - 31000
    You are really working on my nerves.

    Do not try to tell me stuff like: "try to read simple interest" or "ur question is not correct".

    You have no idea what you're doing anyway.

    If you want to correct me, please make sure you revise your basic arithmetic next time.

    Thank you.

    - Janvdl.
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