Answer:
625 ft^2
Step-by-step explanation:
Given
--- perimeter
Required
The largest area
The perimeter is calculated as:

So, we have:

Divide both sides by 2

Make L the subject

The area is calculated as:

Substitute 

Open bracket

Differentiate with respect to W

Set to 0; to get the maximum value of W

Collect like terms

Divide by -2

So, the maximum area is:




In order to solve a proportion you need to cross multiply, so you would do:
4x20 and 9xX and you would get...
9x=80
then divide by nine to get
x=8.8888888889
which is technically 8.9
Answer:
288
Step-by-step explanation:
11 days, 21 hours, and 52 minutes have elapsed
(this answer is assuming he would have a normal heart rate of 70 bpm)
First, you would divide 1,200,703 by 70:
1,200,703/70=17,152.9
This is the amount of minutes that have elapsed.
Then, you convert the minutes to hours by dividing by 60:
17,152.9/60=285.8816667 (285 hours and 52 minutes)
This gives you how many hours and minutes have elapsed.
Finally, you calculate the number of days that have elapsed by dividing 285 by 24 (there are 24 hours in a day):
285/24=11.875 (11 days and 21 hours).
Put all of the amounts together to get the final answer:
11 days, 21 hours, and 52 minutes have elapsed