A computer security expert is investigating a particularly dangerous strain of malware. She determines that the malware has approximately a 42% chance of infecting a typical computer setup. Her company knows that 30 of its computers were exposed to the malware. a. If possible, using a normal approximation of the binomial distribution, find the probability that:

1. none of the computers were infected;

2. all of the computers were infected;

3. exactly 10 computers were infected;

4. more than 20 computers were infected.

b. The expert makes $40/h. She estimates it will take her approximately 4.5 hours to remove the malware from infected computers. Based on your calculations above, how much money should the company budget for fixing these computers?