PLZ HLP!:) The weekly sales in thousands of items of a product has a seasonal sales record approximated by (t is time in weeks with t = 1 referring to the first week in the year). During which week(s) will the sales equal 96,990 items?

Question

PLZ HLP!:) The weekly sales in thousands of items of a product has a seasonal sales record approximated by (t is time in weeks with t = 1  referring to the first week in the year). During which week(s) will the sales equal 96,990 items?

anonymous · Answer

attachment

anonymous · Answer

ok so what did you try to do ?

anonymous · Answer

im ost in this cant u cant lol im forced to take a high school calc class and this isnt even calc fml i just cant fail this last test

anonymous · Answer

lost

anonymous · Answer

i know how to plug in formulas thats about it to be honest

anonymous · Answer

im sorry to hear that :(
anyway you have this equation that you gave me
it describes the amount of itmes for a given t (week)

anonymous · Answer

you look for a certain amount of items and find the corresponding t

anonymous · Answer

ok

anonymous · Answer

plug in one for t for everything

anonymous · Answer

no, you want to find t

anonymous · Answer

im 23 this is sad

anonymous · Answer

im 23 as well .. it is fine

anonymous · Answer

but i thought it says t=1 in the problem

anonymous · Answer

:)

anonymous · Answer

no, they say that t=1 means the first week

anonymous · Answer

ahh gotcha

anonymous · Answer

now when you find t , for example if you find t = 10 you know that it is the 10th week in year

anonymous · Answer

now, you got the equation :

n=84.59 + 24.8sin(pi*t/24)

anonymous · Answer

and they ask you for what weeks n = 96,990

anonymous · Answer

i got undefined ...

anonymous · Answer

so you have to solve:

96,990 = 84.59 + 24.8sin(pi*t/24)
i guess here 84.59 means 84590
and 24.8 means 24800

anonymous · Answer

so it is really should be :
96.99 = 84.59 + 24.8sin(pi*t/24)

anonymous · Answer

since they say "n is in thousands of items"

anonymous · Answer

im getting a crazy calculation

anonymous · Answer

http://mathway.com/answer.aspx?p=trig?p=96.99SMB15SMB01SMB1584.59SMB15+SMB1524.8sin(SMB19*tSMB1024)?p=1?p=?p=?p=?p=?p=0?p=?p=0?p=?p=?p=SolveSMB15theSMB15EquationSMB15forSMB15t

anonymous · Answer

why, look:
96.99 = 84.59 + 24.8sin(pi*t/24)
12.4 = 24.8sin(pi*t/24)
0.5 = sin(pi*t/24)

anonymous · Answer

week 4, week 20, and week 52?

anonymous · Answer

wait ill check :)

anonymous · Answer

0.5 = sin(pi/6)

so :
sin(pi/6) = sin(pi*t/24)
1. pi*t/24 = pi/6 + 2pi*k
t = 4 + 48*k
t = 4 , 52

2. pi*t/24 = pi - pi/6 + 2pi*k
t = 20 + 48*k
t=20

so yes! 
4 20 52

anonymous · Answer

yay ur being my life saver right now!!!

anonymous · Answer

THANK U SOO MUCH

anonymous · Answer

yw :))