00:01
Okay, we are told the ship can sail up 30 miles per hour in calm waters.
00:07
We'll assume the gulf stream rate of speed is g miles per hour.
00:13
And we're told in the same time going with the gulf stream.
00:18
It can do 148 miles against the gulf stream, under two miles, in the same time.
00:27
Well, the first thing is use the formula for speed.
00:30
Speed is distance over time now with the gulf stream your speed is 30 plus g i .e.
00:42
The speed in still water if you like or calm water plus the golf's stream helping you along distance traveled with the gulf stream your toes 148 miles time taken call it t.
01:00
Against the gulf stream going slower overall 30 for the speed of the boat, take away the current you're fighting, and now we're going only 92 miles in the same time.
01:15
So, 92 over t.
01:17
So this t and that t are the same time.
01:23
Well, we have here two equations and two unknowns.
01:27
So maybe add them up first, see what happens.
01:31
And we get 60 on the left, and we end up with the g's canceling out...