5. A user invokes an app that writes a file. The app displays a progress bar that shows how much of the file has been written. Just as the progress bar reaches 50%, the power fails and the computer stops. When power is restored and the computer rebooted, the user discovers that less than 20% of the file was actually written. What might explain why the app report 50% when, clearly, only 20% of the file had actually-been written? A user invokes an app that writes a file. The app displays a progress bar that shows how much of the file has been written. The progress bar has been advancing quickly, but just as the progress bar reaches 99%, the progress bar seems to freeze, then after a delay the bar show 100%, then disappears, and the app GUI moves on to another phase of activity, what might explain why the progress bar seemed to freeze for a time at 99% complete before reporting 100% complete and moving on? 6