Question

on Mindy's guitar, the frequency of a vibrating string varies inversely as the length of the string. When a guitar string of "s" inches in length that vibrates at a frequency of 80 cycles per second is shortened to 6 inches in length, it vibrates at a frequency of 120 cycles per second. What is the value of "s"?

Answer 1

F1/F2 = L2/L1

80/120 = 6/s
80s = 720
<b>s = 720/80 = 9</b>

check:

is 80/120 = 6/9 ?
80/120 = 2/3
and
6/9 = 2/3

looking good!