Question

It costs $2200 to make 100 chairs and $4800 to make 300 chairs. Express the cost as a function of the number of chairs produced, assuming its linear.

Answer 1

i understand to find the slope you have to do y2-y1/x2-x1

Answer 2

then its y=13x+ 9

Answer 3

but then the intercept would be 0, 9

Answer 4

but you can make 0 chairs and it cost $9

Answer 5

you cant*

Answer 6

am i right?

Answer 7

m = (4800 - 2200)/(300-100) = 2600/200 = 13

then recall the equation of a line through a point (x1,y1)

y-y1 = m(x-x1)

y - 4800 = 13(x- 300)

y - 4800 = 13x - 3900

y = 13x +900

Answer 8

but if you make 0 chairs it cant cost $900 right?

Answer 9

do i just use that equation n put a restriction on it?

Answer 10

y= 13x+900 when x>0 ?????????

Answer 11

the maths isn't wrong, i would explain this problem by saying its just a model and models aren't perfect. maybe they make so many chairs usually it doesn't matter what the model says happens at zero

Answer 12

in the question it says they are making 100 or 300 chairs. maybe there is a minimum chair number we do not know about

Answer 13

o ok thx!!!!

Answer 14

happy to help :)