so confused :( 2 pre-calculus questions that have stumped me??

I just don't understand these! :( I can't get number one to show up on my graphing calculator (even when i change the window proportions), and number two...what?? If anyone can show their work and provide explanations so I can understand/learn these concepts, please, please, please do so! (Crying)

**QUESTIONS:**

1.) **"use a graphing utility to graph the sales function over 1 year, where S is the sales in thousands of units and 't' is the time in months, with t=1 corresponding to January. Determine the months of maximum and minimum sales."**

**function:** *S = 74.50 + 43.75 sin (pi times t)/6*

-------------------

2.) **The motion of an oscillating weight suspended by a spring was measured by a motion detector. The data was collected, and the approximate maximum displacements form equilibrium (y=2) are labeled in the figure. The distance y from the motion detector is measured in centimeters and the time t is measured in seconds.**

http://i55.tinypic.com/jr3ekm.jpg

**b.) approximate the amplitude and period**

c.) find a model for the data