Answer:
required probability is .3446
Step-by-step explanation:
It is given that most expected time of completion = 90 days
Variance = 25
We know that
[tex]\sigma =\sqrt{Variance}\\\\\sigma =\sqrt{25}\\\sigma =5[/tex]
Thus the standard normal deviate is given by
[tex]Z=\frac{X-\bar{X}}{\sigma }[/tex]
Applying values we get
[tex]Z=\frac{88-90}{5}\\\\Z=-0.4[/tex]
Using the standard table for Z we have probability corresponding to Z = -0.4 equals 0.3446
Thus required probability is .3446