Answer:
95.15%
Step-by-step explanation:
We have that the mean (m) is equal to 20, the standard deviation (sd) 3
They ask us for P (x <25)
For this, the first thing is to calculate z, which is given by the following equation:
z = (x - m) / sd
We have all these values, replacing we have:
z = (25 - 20) / (3)
z = 1.66
With the normal distribution table (attached), we have that at that value, the probability is:
P (z <1.66) = 0.9515
Which means that the probability that it arrives before 25 minutes is 95.15%
