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You are correct. Mountains are part of the lithosphere.
Answer:
Amplitude is decreased by a factor of
if intensity is decreased by a factor of 3.
Explanation:
Intensity of a sound wave is directly proportional to the square of its amplitude.
Therefore, if intensity is
and amplitude is
, then
, where,
is constant of proportionality.
Now, if intensity of sound wave is decreased by a factor of 3. So,
New intensity is, 

Plug in
for
. This gives,

Therefore, amplitude is decreased by a factor of
.
Answer:
Insulation helps to prevent that transfer of heat.