Answer:
a) For this case we have 4 programs so then if we define the event R that a CD is tested we have the following probability for each test:

The failure probability for each program are given by:

For this case we assume that each test is independet form the others.
We can calculate the probability that all 4 programs works properly like this:

So then the probability that any program fails would be given by:
And if we use the fact that we have 4 possible test the true probability of interest would be:

b) 
And replacing we got:
![p =(1-0.01)*(1-0.01) *[1- (1-0.03)(1-0.02)]= 0.99*0.99*[1- 0.97*0.98]= 0.0484](https://tex.z-dn.net/?f=%20p%20%3D%281-0.01%29%2A%281-0.01%29%20%2A%5B1-%20%281-0.03%29%281-0.02%29%5D%3D%200.99%2A0.99%2A%5B1-%200.97%2A0.98%5D%3D%200.0484)
c) From part a we now that the probability that any program fails would be given by:

So then if we have 100 CDs the expected number of rejected Cd's are:

Step-by-step explanation:
Part a
For this case we have 4 programs so then if we define the event R that a CD is tested we have the following probability for each test:

The failure probability for each program are given by:

For this case we assume that each test is independet form the others.
We can calculate the probability that all 4 programs works properly like this:

So then the probability that any program fails would be given by:
And if we use the fact that we have 4 possible test the true probability of interest would be:

Part b
For this case we want the probability that it failed program 2 or 3
So then we can find this probability like this:

And replacing we got:
![p =(1-0.01)*(1-0.01) *[1- (1-0.03)(1-0.02)]= 0.99*0.99*[1- 0.97*0.98]= 0.0484](https://tex.z-dn.net/?f=%20p%20%3D%281-0.01%29%2A%281-0.01%29%20%2A%5B1-%20%281-0.03%29%281-0.02%29%5D%3D%200.99%2A0.99%2A%5B1-%200.97%2A0.98%5D%3D%200.0484)
Part c
From part a we now that the probability that any program fails would be given by:

So then if we have 100 CDs the expected number of rejected Cd's are:
