IT computer memory
posted by freddo on .
Hi,
Can someone check this for me please..
18 MB of data are to be transmitted over a a megabyte per second connection. How long should the complete transaction take, to the nearest 0.1s.
Size of file / data rate so,
18MB x 10^6 x 8 bits = 144,000,00
4 megabits per second = 4 x 10^6 = 4,000,000 bits per second
so the download time will be
144,000,000 / 4,000,000 = 36 seconds
my answer is 36 seconds is that right
next ,....
a 50 MB file compressed using a ratio of 10 what is the compressed file size
50MB / 10 = 5 MB
Is this correct ???
Thanks you

You have to double check the question:
"18 MB of data are to be transmitted over a a megabyte per second connection"
Is it "a" megabyte connection" or is it "4 megabit connection"? 
Hi
Sorry wasn't too clear
This should read 18MB of data are to be transmitted over a 4 megabits per second connection ... how long would it take to complete the transaction 
to the nearest 0.1 s

For the second part of your question...
Compressed file size = uncompressed / compression ratio
so
Compressed file size = 50MB / 10
Compressed file size = 5MB
I think 
No, incorrect.
Be carefull with this, your:
18MB x 10^6 x 8 bits = 144,000,00
Should in fact be:
18mb x 2^20 x 8 bits = 150,994,994
Your second part is correct, so its
4 megabits per second = 4 x 10^6 = 4,000,000
Answer:
150994994 / 4000000 = 37.75 seconds.