How to find the indicated probability

X has a normal distribution with the given mean and standard deviation. Find the indicated probability.

μ = 60, σ = 10, find P(40 ≤ X ≤ 65)

P(40 ≤ X ≤ 65)= P[ (40-60)/10 ≤ z ≤ (65-60)/10 }

= P(-2 ≤ z ≤ 0.5) = 0.6687 <---------