So how do we figure out that area right over there? Well, we could use a z-table. We could say how many standard deviations above the mean is 25 liters? Well, it is five liters above the mean. So let me write this down. So the z here, the z is equal to 25 minus the mean, minus 20, divided by the standard deviation for, I guess you could say, this combined normal distribution. This is two standard deviations above the mean, or a z-score of plus two.