The period of the musical node e0 is 4.85 × 10-2 seconds. what is the frequency of this note? select one of the options below as your . a. 10.8 hertz. b. 20.6 hertz. c. 40.8 hertz. d. 48.5 hertz. e. 80.9 hertz

Here's an interesting factoid to remember:

                  (Period of any wave) x (Frequency of the wave)  =  1 .

If you can memorize that, then you'll always remember that

                       Period  =  1 / frequency
and
                 Frequency  =  1 / period .

The second one is what you need for this problem.

                 Frequency  =  1 / period

                                     =  1 / (4.85 x 10⁻² second)

                                     =  1 / (0.0485 second)

                                     =     20.62 / second

                                     =     20.62 Hz.    (rounded)