Answer:
Z = (60 - x + y + z) / √a + b + c
Step-by-step explanation:
Since it is a normal distribution, we must calculate the mean and standard deviation, since we do not have data, what we will do is leave them based on these:
Thus Total Mean time = M1 + M2 + M3
given:
M1 = x
M2 = y
M3 = z
Total Mean Time M = x + y + z
Now to calculate the standard deviation we first calculate the variance.
The total Variance V = V1 + V2 + V3
Given:
V1 = a
V2 = b
V3 = c
V = a + b + c
Thus Standard deviation SD of the complete operation is
SD = √ V
SD = √a + b + c
we need to find the probability that the mean time is less than or equal to 60 minutes, the first thing is to find the value of Z.
Formula of Z is:
Z = (X - M) / SD
In this case X = 60.
On plugging the values we get
Z = (60 - x + y + z) / √a + b + c
refer to the Z table and find the Probability of Z ≤ (60 - x + y + z) / √a + b + c
