Check the picture below.
is simply a 9x9 square, so its perimeter is simply 4*9.
Probability of survival of one disk, p=1-0.05=0.95
If there are n drives, and failures are independent (e.g. mechanical wear and tear, and not a lightning strike or a current spike), then
Probability of survival = p^n
(a) for two disks, P(2) = 0.95^2=0.9025
(b)for three disks P(3) = 0.95^3 = 0.8574
-4 x is less than -4
x < -4
33 because 6x5=30 then plus 3 equals 33
As, order is important so we use permutation,
total no. of students= n=8
selected students= r=3
nPr= n!/(n-r)! = 8!/(8-3)! =336 different ways
