#### Answer

100 chirps per minute

#### Work Step by Step

Using the formula T = 50 + $\frac{N - 40}{4}$, substitute the value given into the equation.
65 = 50 + $\frac{N - 40}{4}$
Solve for N:
15 = $\frac{N - 40}{4}$
60 = N - 40
100 = N
Interpret: 100 chirps per minute