let n1 harmonic is corresponding to 50.7 cm & n2 harmonic is corresponding 83.9 cm
∴2λ=(83.9−50.7)cm2λ=33.2cm
λ=66.4cm∴4λ=16.6cmLength corresponding to fundamental mode must be close to 4λ & 50.7 cm must be an odd multiple of this length 16.6×3=49.8cm.therefore 50.7 is 3rd harmonicIf end correction is e, thene+50.7=43λcm Speed of sound, v=fλ∴v=500×66.4 cm/sec =332.000m/s