SOLUTION: Please help! Each Saturday for 10 weeks, Doris performs the same exercise routine and scores her energy level from 1-10. Her scores fluctuate over the weeks according to the func

Algebra ->  Trigonometry-basics -> SOLUTION: Please help! Each Saturday for 10 weeks, Doris performs the same exercise routine and scores her energy level from 1-10. Her scores fluctuate over the weeks according to the func      Log On


   

Question 941310: Please help!
Each Saturday for 10 weeks, Doris performs the same exercise routine and scores her energy level from 1-10. Her scores fluctuate over the weeks according to the function e(w)=4sin(3.14/4)w+5 where w is the week number. During which week does Doris score her energy at a level 5?
A. Weeks 2 and 6
B. Weeks 2 and 10
C. Weeks 4 and 8
D. Weeks 5 and 7
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
I believe you meant e%28w%29=4sin%28%28pi%2F4%29w%29%2B5 .
e%28w%29=5 means 4sin%28%28pi%2F4%29w%29=0--->sin%28%28pi%2F4%29w%29=0
That happens when
%28pi%2F4%29w is 0 , pi , 2pi , etc.
%28pi%2F4%29w=0--->w=0 , but we do not have a week zero.
%28pi%2F4%29w=pi--->w%2F4=1--->highlight%28w=4%29
%28pi%2F4%29w=2pi--->w%2F4=2--->highlight%28w=8%29