Question

A company has determined that the number of items it sells varies inversely as the price of the item. If 20,000 items can be sold if the price is $9.50, how many items can be sold of the price is $8.75? Round your answer to the nearest whole number.

Answer 1

Let N be the number of items sold and p the price. 
Since the variation is inverse, then the relation between N and p is:
$N=k\dfrac{1}{p}$
For N=20000 and p = $9.5, we get the formula:
 $20000=k\dfrac{1}{9.5}\\p=20000\times9.5=190000$
If p = 8.75, then the number of items sold can be computed using the formula:
$N= 190000\dfrac{1}{8.75}=21714 \text{ total items}$