Question 1204408
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1 year = 52 weeks approximately


Desmos Graph
<a href="https://www.desmos.com/calculator/4eidoto8nc">https://www.desmos.com/calculator/4eidoto8nc</a>


The Desmos graph shows the sine function f(x) = 20*sin( (pi/13)x ) + 2, along with the horizontal line y = 15.


On the domain 0 < x < 52, the intersection points are approximately:
A = (2.928,15)
B = (10.072,15)
C = (28.928,15)
D = (36.072,15)


The gap from A to B is one chunk of time when the temperature is above 15 degrees Celsius.
10.072-2.928 = 7.144, which is about 7 weeks.


The gap from C to D is another chunk of time when the temperature is above 15 degrees Celsius.
36.072-28.928 = 7.144, also about 7 weeks.


The total would then be roughly 7+7 = 14 weeks out of the 52 week timespan.


Edit: The student has mentioned the textbook's answer is 14.29
This is because 2*7.144 = 14.288 which rounds to 14.29
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