SOLUTION: five years ago the population was at 1600 and today only 1000 of the birds are alive. once the population drops below 300 its irrevesible. when will this happen? years from now/

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Question 1010572: five years ago the population was at 1600 and today only 1000 of the birds are alive. once the population drops below 300 its irrevesible. when will this happen? years from now/
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Plot population +p+ on the vertical axis
Plot time +t+ in years on the horizontal axis
You are given two points on a straight line:
( -5, 1600 )
( 0, 1000 )
-------------
Use the general point-slope formula to
find the equation
+%28+p+-+1000+%29+%2F+%28+t+-+0+%29+=+%28+1600+-+1000+%29+%2F+%28+-5+-+0+%29+
+%28+p+-+1000+%29+%2F+t+=+600+%2F+%28-5%29+
+%28+p+-+1000+%29+%2F+t+=+-120+
+p+-+1000+=+-120t+
+p+=+-120t+%2B+1000+
--------------------
+300+=+-120t+%2B+1000+
+120t+=+1000+-+300+
+120t+=+700+
+t+=+5.833+
In 5 years and 10 months, population drops below 300
------------------
check:
( -5,1600 )
+p+=+-120t+%2B+1000+
+1600+=+-120%2A%28-5%29+%2B+1000+
+1600+=+600+%2B+1000+
+1600+=+1600+
OK
( 0, 1000 )
+p+=+-120t+%2B+1000+
+1000+=+-120%2A0+%2B+1000+
+1000+=+1000+
OK
( 5.8333, 300 )
+p+=+-120t+%2B+1000+
+300+=+-120%2A5.8333+%2B+1000+
+300+=+-700+%2B+1000+
+300+=+300+
OK