P. 4448. The speed of sound in carbon dioxide is 1.3 times as much as that of in air. Two children, sitting 2 and 2 metres from the opposite sides of a balloon which is filled with carbon dioxide, and hanged in the height of the heads of the children, found that the balloon ``reinforce'' their whisper the most, exactly at this position.
Estimate the diameter of the balloon.
Deadline expired on 11 June 2012.