00:01
A speedboat can travel 32 miles per hour in still water.
00:04
That means it's without any current.
00:07
It travels 150 miles upstream against the current.
00:14
So what's going to happen to the current? the current is going to slow you down.
00:18
So his speed here is going to be 32 minus the speed of the current, which we're going to put as x.
00:24
Then returns to the starting location.
00:29
So the starting rotation, he's going to return this way, where his speed is going to be 32 plus x, and he's going to have the same distance because he's returning to that location.
00:42
So we also know the speed of the current.
00:45
They tell us the time is a total of 10.
00:48
So the time upstream plus the time downstream equals to 10.
00:54
So what's our time? distance equals rate times time.
00:58
So distance divided by rate is going to be our time.
01:02
So we're going to have 150 divided by 32 minus x, that's upstream, plus 150 divided by 32 plus x, equals to 10.
01:13
Here we have an equation.
01:15
Let's solve it by multiplying through about 32 minus x and 32 plus x.
01:22
32 minus x, 32 plus x.
01:25
And then the same thing here...