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A string is clamped at both the ends and it is vibrating in its 4 th harmonic. The equation of the stationary wave is Y = 0.3 sin(0.157x) cos(200 π t). The length of the string is : (All quantities are in SI units.)

1. 40 m
2. 80 m
3. 20 m
4. 60 m

Correct answer: 80 m

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