Total Uptime = 91.25 days(Given)
Total Downtime = 5 mins. =5/60 hrs. = 0.083 hrs. (Given)
Now substitute these values in the expression:
Availability = Total uptime/(total uptime+total downtime)
Availability = {91.25*24/(91.25*24+0.083)*100}.
= (2190/ (2190+0.083))*100
= (2190/2190.083)*100
= 0.9996211481*100
= 99.9962%
Answer is option (4)