Author 
Topic 

jfg4707
Average Member
USA
19 Posts 
Posted  10/05/2007 : 14:15:33

Hi,
I would like to know if I have answered the following questions correctly.
Problem A company sells S(t) thousand electric blankets in month t (with t=0 being January), where the approximate value of S(t) is given by S(t) = 72.25 + 41.5 sin(/6t + /2). Find the function's period and amplitude and explain their practical significance. Also, when does the period begin for this function?
Solution The amplitude is A = 41.5. It's practical significance is that it represents the averge sales over the year.
The period is given by P = 2/B = (2)/(/6) = 12. The period tells us the number of months for the sales to go through a complete cycle, i.e., 12 months.
The function has a horizontal shift to the left given by C/B = (/2)/(/6) = 3. Hence, the period begins in October.
Thank you for any help you can give me. 


tkhunny
Advanced Member
USA
1001 Posts 
Posted  10/05/2007 : 14:45:26

Everything but Amplitude. Try that again. I think 72.25 is the average sales. 41.5 dances around 72.25. 


jfg4707
Average Member
USA
19 Posts 
Posted  10/05/2007 : 15:27:53

Thank you, tkhunny.
Yes, the midline (or line of oscillation) is the average sales for the year. The amplitude, 41.5, then, is amount of variation from that averge in a positive and a negative direction (or, the high and low variation from the average). 



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