00:01
We want to find the average cost of the rental card during different periods.
00:05
And this is kind of a step function is what this is referred to as, kind of like the cost of stamps over time.
00:13
And therefore, we'll go ahead and find the average here.
00:18
So by day four, we've now paid a total of $144.
00:24
And we could verify that with the graph.
00:26
And then we want to divide that by the four days, and this gets us an average cost of $36 per day.
00:35
That makes sense because that's the rate per day.
00:39
For number five, same idea, add up the cost over five days.
00:43
That would end up being 36 times five, divide that back by five, and then that would get us again back to $36.
00:57
But day six is when it starts to get a little funky, because the cost stays the same.
01:02
The rental car is free for days through day five, six, and seven.
01:09
And so we're going to divide that then by six.
01:13
And then this will reduce our average cost down to 30.
01:21
And then it's going to continue to be optimized because day seven then is the best deal through day seven, because then it's still 180, but then divided by seven.
01:34
The accumulated cost after five days, but really it's seven days...