To determine the approximate time it takes to transfer a 1 GB file over a 10 Mbps Ethernet LAN with a 20% degradation in bandwidth due to Ethernet overheads, we can use the following steps:
Step 1: Calculate the effective bandwidth after the 20% degradation.
Effective bandwidth = 10 Mbps - (20% of 10 Mbps) = 10 Mbps - (0.2 * 10 Mbps) = 10 Mbps - 2 Mbps = 8 Mbps
Step 2: Convert the file size from gigabytes to megabits.
1 GB = 1,024 MB
1 MB = 8 megabits
File size = 1,024 MB * 8 megabits/MB = 8,192 megabits
Step 3: Calculate the time taken to transfer the file using the effective bandwidth.
Time = File size / Effective bandwidth
= 8,192 megabits / 8 Mbps
= 1,024 seconds
Step 4: Convert the time from seconds to minutes.
1 minute = 60 seconds
Time = 1,024 seconds / 60 seconds/minute
≈ 17.07 minutes
Therefore, the approximate time it takes to transfer a 1 GB file over a 10 Mbps Ethernet LAN with a 20% degradation in bandwidth is approximately 17 minutes.
Now let's go through each option to determine the correct answer:
Option A) 1 hour - This option is incorrect because the calculated time is approximately 17 minutes, not 1 hour.
Option B) 30 minutes - This option is incorrect because the calculated time is approximately 17 minutes, not 30 minutes.
Option C) 15 minutes - This option is correct because the calculated time is approximately 17 minutes, which is closest to 15 minutes.
Option D) 5 minutes - This option is incorrect because the calculated time is approximately 17 minutes, not 5 minutes.
The correct answer is option C) 15 minutes.