Consider a popular sports news site. At a given moment, 20,000 concurrent users submit a request (a transaction. T) once every 2 minutes on average. Each transaction requires the webapp to download a new article that on average has 3k bytes in length. What is the throughput? 

The correct answer is 4 megabits per second 

EXPLANATION:

• First, we need to determine the amount of data transferred in one transaction.
• The length of an average article is 3k bytes.
  • In terms of bits, this would be 3000 bytes * 8 bits/byte = 24000 bits.
• Next, let's calculate the total amount of data transferred in one minute.
  • There are 20,000 users, each of whom submits a request once every 2 minutes.
  • Therefore, in one minute, there will be 20,000 users / 2 = 10,000 transactions.
• For each transaction, we've determined that there are 24,000 bits.
  • So, the total amount of data transferred in one minute is 10,000 transactions * 24,000 bits/transaction = 240 x 10⁶ bits.
• Since this question asked for throughput in megabits per second, we need to convert this quantity.
  • 1 minute = 60 seconds,
  • therefore, throughput = 240 x 106 bits/minute / 60 seconds/minute
  • =  4 x 106 bits/second = 4 megabits/second. (megabits = 10⁶)

So, the answer is: 4 megabits per second