Circumference = π × diameter
π × 9 = 28.274333882
To 1dp = 28.3
Circumference = 28.3 inches
The way you have it is correct because root 2 is roughly 1.4 pi approximately is 3.4 and 4.5 is a rational number
The probability is found from a suitable table or probability calculator.
p(z < 1.3) ≈ 0.9031995154