Z = (40 – 29)/6 = 1.83

Step 2 Use z-table to find the area below z = 1.83

From the table of Z scores P(X > 40)= P(Z>1.83) = 1 – 0.9664 = 0.0336

We subtract 0.9664 from 1, because we want the probability of BMI greater than 40.

Alternatively, you can do this all in one step with R using the following command

1-pnorm (40, 29, 6)