If you are asked to find the 85th percentile, you are being asked to find a data value associated with an area of 0.85 to its left.
Percentile is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall. For example, the 30 th percentile is the value below which 20% of the observations may be found.
We have:

Then we use trigonometric identities to change the negative sign of the trigonometric functions, so:

We clear f(x):

we simply what we can:

Thus, the correct answer is;
Answer:
one hundred twenty million five hundred forty thousand
Area=length times width
area=10.5
length=3.5
10.5=3.5 times width
divide both sides by 3.5
3=width
width=3ft