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.
Well, seeing the information above, he used 5/8 of paint to paint the fence and table top. If he only had 1/8 left of the paint, he used 2/8 on the chair.
I found the 5/8 because I needed a common denominator. I multiplied the top and bottom by 2 to get 2/8. 3/8+2/8=5/8, and then I added 2/8 to the 5/8 that then gave me 7/8 of paint used, and 1/8 of paint left.
Hope I helped!
If we dialate a function we are just changing what the graph looks like by a stretch or a compression, the function really doesn't change. If a function before the dilation, then it is a function after the dilation. The opposite is also true.