Set it up as a direct proportion:
2.0lb/9hb = x/100hb
solve x (100hb •2.0lb)/9hb = 22.2lb
22.2lbs
From the definition of average velocity,
,
and the fact that constant acceleration means

we can solve for the time
:

Answer:

Explanation:
To solve this problem we use the formula for accelerated motion:

We will take the initial position as our reference (
) and the downward direction as positive. Since the rock departs from rest we have:

Which means our acceleration would be:

Using our values:

The diagram is missing; however, we know that the intensity of a sound wave is inversely proportional to the square of the distance from the source:

where I is the intensity and r is the distance from the source.
We can assume for instance that the initial distance from the source is r=1 m, so that we put

The intensity at r=3 m will be

Therefore, the sound intensity has decreased by a factor

.
The Winter...? I think...? Ya, it's the Winter. :)