Answer:
0.6472 = 64.72% probability that a randomly selected page does not need to be retyped.
Step-by-step explanation:
In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:
In which
x is the number of sucesses
e = 2.71828 is the Euler number
is the mean in the given interval.
Poisson distribution with an average of three errors per page
This means that 
What is the probability that a randomly selected page does not need to be retyped?
Probability of at most 3 errors, so:

In which
Then

0.6472 = 64.72% probability that a randomly selected page does not need to be retyped.
Step-by-step explanation:
By using Ms Excel you should do this problem.
Kindly check the attachment for solution and cell reference for the clear understanding.
Answer:
414
Step-by-step explanation:
n is our variable, so substitute n for 26.
50 + (14*26)
264 + 50 = 414
500*500*500*500*500*500*500*500*500*500 that will = 50,000