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

• Oct 13th 2010, 12:36 PM
lollilikeslife
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
• Oct 13th 2010, 01:07 PM
pickslides
Quote:

Originally Posted by lollilikeslife

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

what kind of graphing calculator do you have?

Quote:

Originally Posted by lollilikeslife

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

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.

b.) approximate the amplitude and period
c.) find a model for the data

Where is the figure?
• Oct 13th 2010, 01:32 PM
lollilikeslife
Quote:

Originally Posted by pickslides
what kind of graphing calculator do you have?

Where is the figure?

graphing calculator: TI-84 Plus

figure: oops! sorry! here is the figure for number 2:
http://i55.tinypic.com/jr3ekm.jpg
• Oct 13th 2010, 01:34 PM
skeeter
Quote:

Originally Posted by lollilikeslife
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.

b.) approximate the amplitude and period
c.) find a model for the data

#2 ... what figure?
• Oct 14th 2010, 03:59 AM
HallsofIvy
Quote:

Originally Posted by lollilikeslife
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."
[snip]

One of the first things you should have learned about the "sine" function is that its largest value is 1 and its least value is -1. Those occur at sin(pi/2) and sin(3pi/2). For what t is pi t/6= pi/ 2? What what t is pi t/6= 3pi/2?

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