Answer:
if repetition is allowed, 
if repetition is not allowed.
Step-by-step explanation:
For the first case, we have a choice of 26 letters <em>each step of the way. </em>For each of the 26 letters we can pick for the first slot, we can pick 26 for the second, and for each of <em>those</em> 26, we can pick between 26 again for our third slot, and well, you get the idea. Each step, we're multiplying the number of possible passwords by 26, so for a four-letter password, that comes out to 26 × 26 × 26 × 26 = possible passwords.
If repetition is <em>not </em>allowed, we're slowly going to deplete our supply of letters. We still get 26 to choose from for the first letter, but once we've picked it, we only have 25 for the second. Once we pick the second, we only have 24 for the third, and so on for the fourth. This gives us instead a pretty generous choice of 26 × 25 × 24 × 23 passwords.
Answer:
The expected total amount of time the operator will spend on the calls each day is of 210 minutes.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean 
and standard deviation 
, the z-score of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
n-values of normal variable:
Suppose we have n values from a normally distributed variable. The mean of the sum of all the instances is 
and the standard deviation is 
Calls to a customer service center last on average 2.8 minutes.
This means that 
75 calls each day.
This means that 
What is the expected total amount of time in minutes the operator will spend on the calls each day
This is M, so:
The expected total amount of time the operator will spend on the calls each day is of 210 minutes.
Answer:
10.5
Step-by-step explanation:
27 / 2 = 13.5, 13.5 - 3 = 10.5
It is 4.............4.............4
To do this make x and y equal 0, y-intercept is at x=0, and x-intercept is at y=0:
x-intercept:
2x+7(0) = -14
2x = -14
x = -7
y-intercept:
2(0) + 7y = -14
7y = -14
y = -2
