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 Post subject: Statistics & Problem Solving book problem page 77 # 49Posted: Wed Apr 28, 2010 3:09 am

Joined: Fri Mar 19, 2010 1:02 pm
Posts: 1
HI, got problem understanding the way this problem could be solved without plugging in answer choices. After stating the two equations I can't go on. Probably I miss some basic knowledge, don't know...

I get stuck here:
Price * Quantity = 568000
(Price + 1000)*(Quantity - 5)= 594000
so
1000*Quantity - 5*Price = 31000

and that's it....

Hope can hels.

Cheers

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 Post subject: Re: Statistics & Problem Solving book problem page 77 # 49Posted: Wed Apr 28, 2010 5:20 pm

Joined: Thu Feb 12, 2009 6:32 pm
Posts: 497
p = old price
n = old qty

(p + 1000)(n - 5) = 594000

and

(p)(n) = 594000 - 26000 = 568000 ... or p = 568000/n

pn -5p + 1000n - 5000 = 594000

pn - 5p + 1000n - 599000 = 0 .... substitute for p

568000 - 5*568000/n + 1000n - 599000 = 0

divide each term by 1000

568 - 5*568/n + n - 599 = 0

5*568/n + n - 31 = 0 ... mutilple each term by n

5*568 + n^2 - 31n = 0

n^2 - 31n + 5*568 = 0

try the answer choices (remember, we want the number sold at the new
price, but we have defined "n" as the number sold at the old price)

so, if an answer choice is 71, put in 71+5 = 76 for n in the above.

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