From looking at a periodic function, we had to decide on the equation for it. I got:

Question

y = 1.05 sin x2pi/11.72 + 1.55

1.05 is the 'a' value of the equation
2pi/11.72 is the 'b' value for the equation
1.55 is the 'd' value of the equation
we were told not to take into consideration the 'c' value at all.

the minimum of the graph is 0.5, the maximum is 2.6 and 11.72 is the period

the function showed the depth of water on the 16 January and displayed the times of 6am to 11pm (where 6am = 0x, 7am = 1x ....... 11pm = 17x)

The question is asking what time periods will the water be 1.7 and over on the 19 January.

Should I make y = 1.7 and work out the x values that way? Will it matter even though the equation is for the 16 January data, even though I'm using it to find out what time it will be above 1.7 on the 19 January?

Answer 1

Clearly Steve answered this for you in great detail here
http://www.jiskha.com/display.cgi?id=1432801604

Answer 2

ahhhh. I did the solution, but I failed to notice the three-day time difference. So you'll have to analyze the graph several periods later.