You are hiking along a trail in a wide, dry canyon where the outdoor temperature is T = 30.5 C. To determine how far you are away from the canyon wall you yell "Hello" and hear the echo t = 2.65 s later.

If you stood at the same point on a cold morning where the temperature was T₂ = -2.5 degrees C, how long would it have taken for you to hear the echo, in seconds?