Can anyone help with this? Thank you!

Question 1: A brother and sister try to communicate with a string tied between two tin cans. If the string is 7.6m long. has a mass of 30g. and is pulled taut with a tension of 17N. how much time does it take for a wave to travel from one end of the string to the other? [Express answer using two significant figures! Question 2: The fundamental wavelength for standing sound waves in an empty pop bottle is 0.84m. The length of the bottle is 0.21m. What is the frequency of the third harmonic of this bottle? Question 3: An organ pipe open at both ends has a harmonic with a frequency of 4801-12. The next higher harmonic in the pipe has a frequency of 54OHZ. The frequency of the fundamental is 60 Hz. What is the length of the pipe? (Express answer using two significant figures)