Answer:
25.5 days
Step-by-step explanation:
Mean number of days (μ) = 22 days
Standard deviation (σ) = 6 days
Z-score for the 72nd percentile (according to tabulated values) = 0.583
The z-score for any number of days, X, is determined by:
[tex]z=\frac{X-\mu}{\sigma}[/tex]
The value of X that is greater than 72% of the trial times is:
[tex]0.583=\frac{X-22}{6}\\ X=25.5\ days[/tex]
Therefore, 72% of all of these types of trials are completed within 25.5 days.
