Answer:
The standard deviation of the number of runs required is 2447.26
Step-by-step explanation:
For each run, there are only two possible outcomes. Either the program fails, or it does not. The probability of the computer failing during a run is independent of other runs. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The standard deviation for the expected number of trials for r sucesses is:

A computer program has a bug that causes it to fail once in every thousand runs, on average.
This means that 
In an effort to find the bug, independent runs of the program will be made until the program has failed six times. What is the standard deviation of the number of runs required?
This means that r = 6. So

The standard deviation of the number of runs required is 2447.26
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The angle measures in any triangles add up to 180 degrees
The means is the average of a data set
I FOND YOUR COMPLETE QUESTION IN ANOTHER SOURCE.
PLEASE SEE ATTACHED IMAGE.
The width of the rectangle in this case will be given by:
w = x + 5 + x
Rewriting:
w = 2x + 5
The length of the rectangle will be given by:
L = x + 10 + x
Rewriting:
L = 2x + 10
Answer:
w = 2x + 5
L = 2x + 10