Answer:
A - Difference in tides for location C is 6.9 feet and high tide for location A is 8.2 feet.
B - Value of low tide in location D is -0.64 feet.
Explanation:
Part A: We are given,
The table showing the difference between high and low tides.
The difference in tides for location C = 7.34 - 0.44 = 6.9
So, the difference in tides for location C is 6.9 feet.
Also,
i.e.
i.e.
i.e. x = 8.2
So, the high tide for location A is 8.2 feet.
Part 2: We are given, the mean of the low tides for the 4 locations is -0.54
Let, 'x' feet be the value of the low ride in location D.
That is,

That is,

That is,

That is,

That is,

That is, x = -0.64 feet
Hence, the value of low tide in location D is -0.64 feet.