What am I doing wrong in this problem? You need to record an entire collection of your favorite music. It consists of 39 hours of music. Assuming you are using MP3 encoding (MPEG Audio Level III at about 128kb per second), how many CDs will you need? (hint: a CD can store up to 700 MB of information.) I did: 128 kb/s * 3600 * 19 = 8755200 kb (to be coded) Compression ratio: 8 (?) 8755200 * 8 = 70041600 kb (to be coded on CD) One CD can store: (700 MB) = (700) * (2^10) kB * 8 = 5734400 kbits # of CDs needed = 8755200 / 5734400 = 13 CDs. Thanks!