Answer:
0.321 is the probability that their mean printing speed of the sample is greater than 17.99 ppm.
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 17.39 ppm
Standard Deviation, σ = 4.25 ppm
Sample size = 11
We are given that the distribution of printing speed is a bell shaped distribution that is a normal distribution.
Formula:
P(printing speed of the sample is greater than 17.99 ppm.)
P(x > 17.99)

Calculating the value from the standard normal table we have,

Thus, 0.321 is the probability that their mean printing speed of the sample is greater than 17.99 ppm.