Question

Please help! MEDAL + FAN!

The graph below shows the value of Edna's profits f(t), in dollars, after t months:

Answer 1

What is the closest approximate average rate of change for Edna's profits from the 3rd month to the 9th month?

A. −69.75 dollars per month
B. −11.63 dollars per month
C. Six dollars per month
D. Nine dollars per month

Answer 2

I know that the formula for rate of change is \[y^2-y^1/x^2-x^1\] but I don't know why I keep getting 3.70. Another post said the answer is B, but I don't know how they got that answer.

Answer 3

y2 = -24.75
y1 = 41.25

x2 = 9
x1 = 3

Answer 4

would you like me to explain where those numbers came from?

Answer 5

But when I copy and paste the graph, it says:

graph of quadratic function f of t having x intercepts at 6, 0 and 18, 0 and vertex at 12, negative 36 and passes through 3, 49.5 and 9, negative 27.25

So I've been using

\[y^2 = 49.5\]

\[y^1 = -27.25\]

\[x^2 = 3\]

\[x^1 = 9\]

Answer 6

or I guess the first two numbers should be opposite? I'm not sure.

Answer 7

I mean like y^2 = -27.25 and y^1 = 49.5

Answer 8

x1 and y1 go with month 3
x2 and y2 go with month 9

Answer 9

so, yes, y2 should be -27.25 and y1 should be (approximately) 49.5

Answer 10

x1 should be 3 and x2 should be 9

Answer 11

So I would get -12.79

Answer 12

And the closest answer is B. Thanks!