The function
𝑓
f is defined by
𝑓
(
𝑡
)
=
70
+
5
sin
⁡
(
2
𝜋
365
(
𝑡
−
90
)
)
f(t)=70+5sin(
365
2π

(t−90)) for
0
≤
𝑡
≤
365
0≤t≤365. Function
𝑓
f models the temperature of water in a lake, in degrees Fahrenheit,
𝑡
t days since January 1. Based on the model, the predicted temperature of the water will be greater than 72 degrees Fahrenheit for approximately how many days? The options are:
(A) 113
(B) 134
(C) 231
(D) 248

Question

The function 
𝑓
f is defined by 
𝑓
(
𝑡
)
=
70
+
5
sin
⁡
(
2
𝜋
365
(
𝑡
−
90
)
)
f(t)=70+5sin( 
365
2π

(t−90)) for 
0
≤
𝑡
≤
365
0≤t≤365. Function 
𝑓
f models the temperature of water in a lake, in degrees Fahrenheit, 
𝑡
t days since January 1. Based on the model, the predicted temperature of the water will be greater than 72 degrees Fahrenheit for approximately how many days? The options are:
(A) 113
(B) 134
(C) 231
(D) 248