The finished inside diameter of the Piston ring is normally distributed with a mean of 4 inches and standard deviation of 0.01 inch. Below what value of inside diameter will 15% of the Piston ring fall

3.98964 inches

Step-by-step explanation:

We are given;

Mean; μ = 4 inches

Standard deviation; σ = 0.01 inch

Probability = 15% = 0.15

Formula to calculate z-value is given by;

z = (X - μ)/σ

Now, since we are given the probability to be below 0.15,thus;

From z - table attached, the z value that corresponds to a probability of 0.15 is -1.036.

Thus, plugging in the relevant values into the z score equation gives;

-1.036 = (x - 4)/0.01

Cross multiply to give;

-0.01036 = x - 4

x = 4 - 0.01036

x = 3.98964 inches

a

step-by-step explanation:

b is the correct answer