(d) The data density of a Blu-ray disk using a 405-nm laser is 1.5 × 107 bits mm −2
. Disks have an outside diameter
of 120 mm and a hole of 15-mm diameter. How many data bits can be contained on the disk? If a Blu-ray disk can
hold 9,400,000 pages of text, how many data bits are needed for a typed page? (Hint: Determine the area of the disk
that is available to hold data. The area inside a circle is given by A = πr2
, where the radius r is one-half of the
diameter.)