Answer: P(x < 0.285) = 0.0668
Step-by-step explanation:
Since the diameters of pencils produced by the machine are normally distributed, we would apply the formula for normal distribution which is expressed as
z = (x - µ)/σ
Where
x = diameters of pencils produced .
µ = mean diameter
σ = standard deviation
From the information given,
µ = 0.30 inches
σ = 0.01 inches
The probability that the diameter of a randomly selected pencil will be less than 0.285​ inches is expressed as
P(x < 0.285)
For x = 0.285
z = (0.285 - 0.30)/0.01 = - 1.5
Looking at the normal distribution table, the probability corresponding to the z score is 0.0668