Question

Ellen is downloading a file. After 2 minutes, there are 38.4 megabytes left to download. After 8 minutes, there is only 9.6 megabytes left to download. What is the size, in megabytes, of the file.?

Answer 1

find the average download rate.
(38.4 - 9.6) / (2-8) = -4.8 mb/min

that means in the first 2 min she had downloaded 2(4.8) = 9.6 mb

38.4 mb left + 9.6 mb already downloaded = 48 mb total

Answer 2

The size of the file is of 48 megabytes.

Explanation:

8-2 = 6 minutes

38.4 - 9.6 = 28.8 megabytes

As we can see, 28.8 megabytes were downloaded in 6 minutes. Assuming a constanct and non stopped download speed, we can affirm that 4.8 megabytes were download per minute (28.8 / 6 = 4.8). As after 2 minutes, there were 38.4 megabytes left, in order to know the size of the file we have to do the following calculation:

38.4 + (4.8 x 2) = Size of the file

38.4 + 9.6 = 48 megabytes

The size of the file is of 48 megabytes.