Show me a picture of the grid. (The square with the lines)
If you try 6x4, you get 24. When you add 4, it = 28. The same thing with 6x4=24+5=29
Answer:
The 80% confidence interval for the population proportion of disks which are defective is (0.059, 0.079).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
Suppose a sample of 1067 floppy disks is drawn. Of these disks, 74 were defective.
This means that 
80% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
The lower limit of this interval is:

The upper limit of this interval is:

The 80% confidence interval for the population proportion of disks which are defective is (0.059, 0.079).
A= about 75 cents -- This is because you would figure out what 5% is equal to (.05). Then, you would do .05 x 14.90 to get the amount of sales tax you will be paying. By doing this you will get .745 which is approximately .75 which would become 75 cents
b= $15.65 -- For this one, you would do the cents (.75) plus the total (14.90) So you would do 14.90+.75 which = 15.65.
Hope this helped :)