SOLUTION: The cost of making a dress is partly constant and partly varies with the amount of time it takes to make the dress if the dress takes 3 hours to make, it costs 2700naira. If it tak

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: The cost of making a dress is partly constant and partly varies with the amount of time it takes to make the dress if the dress takes 3 hours to make, it costs 2700naira. If it tak      Log On


   

Question 844047: The cost of making a dress is partly constant and partly varies with the amount of time it takes to make the dress if the dress takes 3 hours to make, it costs 2700naira. If it takes 5 hours to make the dress, it costs 3100naira. Find the cost if it takes one and a half hours to make the dress.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Plot cost, C on the vertical axis
Plot time in hours, t on the horizontal axis
Use the general point-slope formula
+%28+C+-+2700+%29+%2F+%28+t+-+3+%29+=+%28+3100+-+2700+%29+%2F++%28+5+-+3+%29+
+%28+C+-+2700+%29+%2F+%28+t+-+3+%29+=+400+%2F++2+
+%28+C+-+2700+%29+%2F+%28+t+-+3+%29+=+200+
+C+-+2700+=+200%2A%28+t+-+3+%29+
+C+-+2700+=+200t+-+600+
+C+=+200t+%2B+2100+
-----------------------
If +t+=+1.5+,
+C+=+200%2A1.5+%2B+2100+
+C+=+2400+ naira
------------------------
Check the equation:
+C+=+200t+%2B+2100+
( 5, 3100 )
+3100+=+200%2A5+%2B+2100+
+3100+=+1000+%2B+2100+
+3100+=+3100+
OK
You can check ( 2700, 3 )