Originally Posted by

**Jaydee** Hello all!

My previous thread was closed; I had a bit of a confusion on one of the forum's rules, which is highly embarrassing. I apologize, but I hope I can be cut some slack as it was my very first post here!

Anyways, I am studying for an upcoming grade 11 Pre-Calc exam, and I have a few questions giving me some trouble. Here is one of them, which I know for sure I am doing incorrectly:

**1. **The number of cups of coffee sold weekly is periodic over the course of a year. The maximum weekly sales of 12,000 cups usually occur around the end of January (week 4). The minimum weekly sales of 2,000 cups usually occur at the end of July (week 30).

The weekly sales can be modeled by a sinusoidal function.

**a)** Write an equation to model the weekly sales of coffee.

*(I attempted and got something like: y = -5000sin[5(x-4)] + 7000 but I’m pretty certain that’s quite off!)*

If someone could help me or walk me through this question, that would be much appreciated. I won't lie, this semester I've been pretty much math-stupid, but if someone explains this question to me I will more than likely grasp it with very little difficulty. My teacher hasn't been doing a very good job at... well... teaching. 60% is the class average and we're fast approaching our last unit! : S

Anyways, thanks in advance,

JD