Draw a diagram to illustrate the problem as shown in the figure below.
The minimum depth of 2.5 m occurs at 12:00 am and at 12:30 pm.
Therefore the period i0s T= 12.5 hours.
The maximum depth of 5.5 m occurs at 6:15 am and at 6:45 pm. Therefore the period of T = 12.5 hours is confirmed.
The double amplitude is 5.5 - 2.5 = 3 m, therefore the amplitude is a = 1.5 m.
The mean depth is k = (2.5 + 5.5)/2 = 4.0 m
The model for tide depth is

That is,
d = -1.5 cos(0.5027t) + 4
where
d = depth, m
t = time, hours
A plot of the function confirms that the model is correct.
Halving-reduce by half or think what is fifty% of the number or divide by two
doubling-add the number you got to the same number or multiply by two
Halving Ex.:6/2=3
Doubling ex.: 9+9=18 or 6*2=12
Base times height equals area of a parallelogram
Answer:
when 6(2+4) -1 divided by 2.3 + 1 the answer is 36.5652174
I believe b is about 16.3, hope this helps