Answer:

Step-by-step explanation:
Remember that 
Then,

But
and 
Then

The submarine is 68 feet below sea level, which is -68
Answer:
The correct answer is D because they are unknown
Step-by-step explanation:
In the question it is given that the length of the blue lake trail is 11 3/8 miles. In the question it is also given that Gemma has hiked for a total time of 3 hours and each hour she has hiked 2 1/2 miles.
Now coming to solving the problem we get:
Total length of blue lake trail = 11 3/8 miles
= 91/8 miles
Distance hiked by Gemma in 1 hour = 2 1/2 miles
= 5/2 miles
Then the total distance hiked by Gemma in 3 hours = (5/2) * 3
= 15/2 miles
The distance left to cover the full trail = (91/8) - (15/2) miles
= (91 - 60)/8 miles
= 31/8 miles
= 3 7/8 miles.
So Gemma is 31/8 miles or 3 7/8 miles from the end of the trail.
So hmm check the picture below
the radius "r" is half the diameter, meaning, the diameter is 2r long
now, if the height "h" is twice "d" or 2d, then that means h = 2(2r)
thus