Multiple choice

A humming bird flaps its wings 80 times in 4 seconds. What is the frequency at which it flaps its wings?

  1. 160 Hertz

  2. 320 Hertz

  3. 20 Hertz

  4. 40 Hertz

  5. 8 Hertz

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Frequency is the number of oscillations per second. So, 80/4 = 20. Thus, the answer is 20 Hz.