Answer:
n = 1067
Step-by-step explanation:
Since nothing is known, we would assume that 50% of the computers use the new operating system. So, standard error = 0.5/SQRT(n)
Z-value for a 95% CI = 1.9596
So, margin of error = 1.9596 x 0.5 / SQRT(n) = 0.03
So, n = 1067 (approx.)
This will be your approximate answer : n = 1067