11 A teacher set up a signal generator connected to two loudspeakers as shown. This apparatus was used to determine the speed of sound in air in an open space. A measuring tape was positioned along the ground at XY, which was a perpendicular distance of 3.00m from the two loudspeakers. Y loudspeaker 1 3.00m signal generator 5.00 m 0 0 loudspeaker 2 X Not to scale The signal generator was set to a frequency of 160 Hz. The students walked along the line KY. As they walked, they heard a series of loud and quiet scunds. At 0 the students heard a loud sound. (a) Explain why the students heard a loud sound at O. (b) As the students moved from 0 towards Y, the sound became quieter until a minimum was reached. One student stood still at the minimum point while another student recorded from the measuring tape the distance from O at which this occurred. He recorded this as 84 cm. (i) Determine the speed of sound in air