ANSWER
The period is
[tex] \frac{1}{60} [/tex]
EXPLANATION
The equation that models the voltage, V, produced in an AC generator at time, t, in seconds is
[tex]V(t)=220 \sin(120\pi(t-1360))[/tex]
The period of this function is given by:
[tex] \frac{2 \pi}{B} [/tex]
Substitute the value of B to get;
[tex] = \frac{2\pi}{120\pi} [/tex]
Simplify
[tex] = \frac{1}{60} [/tex]
