A computer-supply retailer purchased a batch of 1,000 CD-R disks and attempted to format them for a particular application. There were 857 perfect CDs, 112 CDs were usable but had bad sectors, and the remainder could not be used at all.

a. What is the probability a randomly chosen CD is not perfect?

b. If the disk is not perfect, what is the probability it cannot be used at all?

Solution:

Step1 of 3:

A computer-supply retailer purchased a batch of 1,000 CD-R disks and attempted to format them for a particular application .

There are 857 perfect CDs, 112 CDs were usable but bad sectors, and the remainder could not used at all.

- We have to find the probability that a randomly chosen CD is not perfect.
- We have to find the probability that it cannot be used at all, if the disk is not perfect.