Question

What is the final answer?

Answer 1

Answer:  42

Explanation:

We have y = -0.9x^2 + 76x - 250 which is in the form y = ax^2+bx+c

where,

• a = -0.9
• b = 76
• c = -250

The vertex (h,k) is when the profit is maxed out.

h = -b/(2a)

h = -76/(2(-0.9))

h = 42.222 approximately

Let's plug in x values around x = 42

Try x = 41

y = -0.9x^2 + 76x - 250

y = -0.9(41)^2 + 76(41) - 250

y = 1353.10

Now try x = 42

y = -0.9x^2 + 76x - 250

y = -0.9(42)^2 + 76(42) - 250

y = 1354.4

Now try x = 43

y = -0.9x^2 + 76x - 250

y = -0.9(43)^2 + 76(43) - 250

y = 1353.9

We see that the largest profit happens when x = 42.