A String Is Strung Horizontally with a Fixed Tension

Multiple Choice

A string is strung horizontally with a fixed tension.A wave of frequency 90 Hz is sent along the string,and it has a wave speed of 55.1 m/s.Then a second wave,one of frequency 180 Hz,is sent along the string.What is the wave speed of the second wave?
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A) 27.6 m/s
B) 55.1 m/s
C) 110.2 m/s
D) 82.7 m/s
E) 220.4 m/s