[MUSIC] The faucet has a slow leak. 
It's dripping. 
How much water is being wasted? 
Let's find out. 
Now, I'm going to start the timer and see 
how full the measuring cup is after, say, 
three minutes. 
[MUSIC] So, after three minutes of 
dripping, the drip has put approximately 
13 milliliters of water into this 
measuring cup. 
Here, I have a cube that holds one liter 
of liquid. 
How long would it take our dripping 
faucet that drips 13 milliliters per 
three minutes to fill this cube that 
holds 1000 milliliters? 
[MUSIC] Alright. 
It's been about 90 minutes. 
Let's see where we're at. 
It looks like almost exactly 400 
milliliters. 
So, we've collected some data and now, 
let's see if we can figure something out. 
Alright. 
Here at time and time and water. 
After three minutes, we found that 13 
milliliters of water are inside the 
measuring cup. 
This tells us that the water is entering 
the measuring cup at a rate of 13 
milliliters for three minutes, which is 
equal to or approximately [SOUND] 4.3 
milliliters per minute. 
Later, we checked it and we found that 
after 90 minutes, there were 400 
milliliters in the cube this time. 
Well, this tells us since going from here 
to here, we have a difference of 87 
minutes and going from here to here, we 
have a difference of 387 milliliters, 
this gives us a new rate. 
It says, that we have 387 milliliters per 
87 minutes and that's approximately 4.4 
milliliters per minute. 
Aha. 
This looks like it's linear growth. 
I know that the slopes are slightly 
different but such a, such a small 
difference that if we plot it, it should 
be linear. 
Now, at what time is there one liter of 
water in the cube? 
That would be 1,000 [SOUND] milliliters. 
At what time? 
So, we should use t for the variable 
there. 
We have to solve the following equation. 
We want 1000 / t to be approximately 
well, what's between 4.3 and 4.4? 
4.35, okay? 
Ha, ha. 
So now, that's the same as saying, 
t is equal to 1,000 / 4.35 five, this is 
approximately 230 minutes. 
230 minutes is 3 hours, 50 minutes. 
[MUSIC] 
At this point, 3 hours and 50 minutes has 
gone by. 
If we check the cube, [MUSIC] we see it's 
right at a 1,000 milliliters. 
[MUSIC]