You click your fingers in a large hall and hear the echo 0.5 seconds later off the back wall. How far is the back wall? A boat send a sound to the bottom of the ocean and it takes 2 seconds to return to the boat. How deep in the ocean?

Please answer the questions above for 15 points, help desperately needed!:)

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.