The equation y= -5.131x^2 + 31.821x - 3.333 approximates the number of people standing in line to catch a commuter train x hours after 5 am

what is the best estimate for the number of people in line at 7 a. m?
a.) 23
b.) 27
c.) 32
d.) 40

i'm trying to my little sister, but i haven't done sophomore math in a couple of years so i'm not entirely sure, this is for a study guide for her finals so any is really appreciated!

Alright! This question demands that we evaluate


at a given value of x, which was not given directly. But enough information was given to help us determine that value of x.

After 5am, 7am is a two our interval. So we plug in

into the given function to obtain,






But we are dealing with number of people, and we cannot half fractional number of people.
Rounding to the nearest whole number gives,



This means that 2 hours 5am we have 40 people standing in the line to catch up the commuter train.

Its a right angled triangle not a right triangle