Answer:
At least 37.74% of the procedures takes between 97.6 and 125.6 minutes
Step-by-step explanation:
The percentage is the area of the standard normal distribution curve between the values 97.6 and 125.6
The standard normal variate of the given data is found as

Thus for the given values Z is calculated as under

Similarly for the other value we have

Thus the area between the calculated values can be found from standard normal distribution table to be 37.74%
You can't its already simplified
The first thing we must do is find the amount of land that will be used for the 120 lots.
We must remember that 10% of the land will not be used for the lots.
We have then:

Then, we must consider the following conversion of units:

Applying the conversion we have:

Then, the amount of square feet for each lot is given by:
Answer:
There will be 32670 square feet in each lot.