Answer:
It takes Lena 4.1 seconds to compress the accordion completely and then stretch it back out to a length of 50cm.
Step-by-step explanation:
I am assuming the function without a T: [tex]A(t)= 25cos(t)+65[/tex].
The function is graphed in the figure attached, and the blue line is [tex]y =50cm[/tex].
From the graph we see that the accordion is completely stretched (has minimum length) at [tex]t= \pi[/tex] seconds, and stretches back to 50cm at [tex]t=4.069s[/tex]; therefore, it takes Lena 4.069 seconds to stretch the accordion back again, which to the nearest tenth of a second is 4.1s
