Tablet tech support. The technical support desk at a college has set up a special service for tablets. A survey shows that 54% of tablets on campus run Apple’s iOS, 43% run Google’s Android OS, and 3% run Microsoft’s Windows. Assuming that users of each of the operating systems are equally likely to call in for technical support what is the probability that of the next three calls:

a) All are iOS?

b) None are Android?

c) At least one is a Windows machine?

d) All are Windows machines?