'Computer Repair Services' receives on average, 4 service calls every hour. Calculate the following probabilities. There will be no service call in...

a. ‘Computer Repair Services’ receives on average, 4 service calls every hour. Calculate the

following probabilities.

i. There will be no service call in the first 20 minutes.

ii. There will be a service call for the first time between 21 and 33 minutes.

b. The “Mean Time Between Failure” also known as MTBF for a given electronic equipment is 3

years.

i. Calculate the probability that the equipment will fail for the first time between the second and

third year.

ii. If only 10% of the equipment is expected to fail by the end of the first year, what should be

the MTBF for this electronic equipment?

iii. From what you calculated in part “ii.” of this sub-question, describe in your words the

importance of quality control and warranty based recalls of the equipment produced.