00:01
This question, we say that the rate at which people arrive at a theater box office is modeled by the function b, where b of t is measured in people per minute and t is measured in minutes.
00:13
The graph b for t values from 0 to 20 is shown in the figure above, and we ask which of the following is closest to the number of people that arrive at the box office during the time interval from 0 to 20.
00:30
So if i want to figure out the number of people that arrive from this rate, i have to integrate this rate over the appropriate time interval.
00:42
So we are going to be computing the integral from 0 to 20 of b.
00:49
Now in order to evaluate this definite integral, i'm going to be thinking about area, and and we're going to have two pieces of area that we need to consider.
01:02
We're going to have a trapezoid.
01:05
Then we're going to have my triangle.
01:09
So first of all, the area of this trapezoid is half the height.
01:14
So the height is the distance between the parallel bases, in this case 15, times the sum of the bases.
01:22
So half the height times the sum of the bases.
01:25
The bases have lengths of 5 and 15.
01:30
And to that, i'm going to add the area of the triangle...