Answer:
The probability that the sample will contain exactly 0 nonconforming units is P=0.25.
The probability that the sample will contain exactly 1 nonconforming units is P=0.51.
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Step-by-step explanation:
We have a sample of size n=4, taken out of a lot of N=12 units, where K=3 are non-conforming units.
We can write the probability mass function as:

where k is the number of non-conforming units on the sample of n=4.
We can calculate the probability of getting no non-conforming units (k=0) as:

We can calculate the probability of getting one non-conforming units (k=1) as:

Answer: 42.5
Step-by-step explanation:
Another way to solve this is to use the Midpoint Formula. The midpoint of a segment joining points

and

is

So the midpoint of your segment is

Perhaps it helps to see that the x-coordinate of the midpoint is just the average of the x-coordinates of the points. Ditto for the y-coordinate of the midpoint; just average the y's.
She has 501 more pennies than nickles.