Math Is Fun Forum

taylor_2009

Member

Registered: 2010-01-25

Posts: 28

Word problem help?

Let f(x) be the number (in thousands) of computers sold when the price is x hundred dollars per computer. Interpret the statements f(23)=30 and f'(23)=-6. Then estimate the number of computers sold if the price is set at $2325 per computer.

f(23)=30 implies that 30,000 computers are sold when the price is set at $2300.

f'(23)=-6 implies that when the price is $2300, for every $100 price increase, the sales decrease by 6,000 computers.

If computers are sold for $2325 per computer, how many computers will be sold?

I got 2850 computers, but MyMathLab says that isn't right.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Word problem help?

Hi Taylor_2009,

Don't you mean 28500 computers will be sold?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

taylor_2009

Member

Registered: 2010-01-25

Posts: 28

Re: Word problem help?

Thanks! I was just  missing that extra zero. I was working on it late after studying for a calc test all day.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Word problem help?

Hi taylor_2009;

Glad to help. Don't mention this to your teacher but the problem seems to me to be ill posed. The answer 28500 presumes that f(x) is linear. If I choose another idea we get a different answer. The problem does not give me any reason to prefer one model over another. I chose linear because I think I know how your teacher thinks.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

shinylovesme

Member

Registered: 2010-02-16

Posts: 1

Re: Word problem help?

i need help wiv da math problem!!!!!!!!!!

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Word problem help?

Hi shinylovesme;

Where is the problem?

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.