Question 73148
A headset can be manufactured for $.17. The development cost is $150,000. Graph the function that represents the average cost of a head set. About how many must be manufactured to result in a cost of less than than $5 per headset? 
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Let x = number of headsets, y = cost per headset in $
y = (.17x + 150000)/x
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The graph should look something like this
:
{{{ graph( 300, 200, -5000, 50000, -10, 45, (.17x + 150000)/x ) }}}
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To find out how many needs to sold to cost less than $5, solve for x:
(.17x + 150000)/x < 5
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.17x + 150000 < 5x, multiplied both sides by x
:
.17x - 5x < -150000
-4.83x < -150000
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Get rid of the negatives, mult by -1. This reverses the inequality sign
4.83x > 150000
x > 150000/4.83
x > 31,056 have to be sold to bring the cost below $5
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Did this make sense to you?