A server receives 100 requests per second, each taking 0.2 seconds on average (steady state). How many requests are in progress at once on average (Little's law)?

Answer: B. 20

Little's law states that the average number in a system L equals the arrival rate λ times the average time each item spends in the system W. With 100 arrivals per second each staying 0.2 seconds, 20 requests are in progress on average. The law helps size thread pools and buffers, and the same reasoning gives how many outstanding requests are needed to saturate memory bandwidth.

• A. That divides the arrival rate by the time.
• B. Correct. 100 × 0.2 = 20.
• C. That divides the time by the arrival rate.