Step 1 :The average number of cars in the system is 6. This includes both the cars in the line and the car at the window. Every 20 seconds, a car attempts to enter the line, but 40% of them leave because the line is too long. This means that 60% of the cars actually stay and go through the line. We need to find out how long on average a car spends in the system.
Step 2 :We can use Little's Law to solve this problem. Little's Law states that the average number of items in a queuing system equals the average rate at which items arrive multiplied by the average time that an item spends in the system. In mathematical terms, L = λW, where L is the average number of items in the system, λ is the average arrival rate of items to the system, and W is the average time an item spends in the system.
Step 3 :We know that L = 6 and λ = 0.6 cars per 20 seconds (since 60% of cars stay). We need to find W. We can rearrange Little's Law to solve for W: W = L / λ.
Step 4 :Let's calculate W in seconds and then convert it to minutes. L = 6, λ = 0.03, so W = 200.0 seconds. Converting this to minutes, we get W = 3.33 minutes.
Step 5 :The average time a car spends going through the drive-through at Burger Universe is approximately \(\boxed{3.33}\) minutes.