Expert: Sherman D. - 10/22/2008

Question
1.   A company has found that the demand for its product varies inversely as the price of the product. When the price x is 4.5 dollars, the demand y is 400 units. Find a mathematical model that gives the demand y in terms of the price x in dollars. Approximate the demand when the price is 8 dollars.

2.Suppose p varies directly as the square root of q.If p= −2 when q = 15, what is p if q is 1?


thank you


Answer
1.)
y = k/x

400 = k/4.5
1800 = k

y = 1800/8
y = 225

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2.)
p = sqrt(q)k

-2 = sqrt(15)k
k = -2/sqrt(15) or k = -2sqrt(15)/15

p = -2sqrt(15)/15 * sqrt(1)
p = -2sqrt(15)/15

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