Answer:
66.98 db
Explanation:
We know that

L_T= Total signal level in db
n= number of sources
L_S= signal level from signal source.

= 66.98 db
The change of color. Each color has a different wavelength therefore a different frequency.
Dependent on what you are measuring and what took you are using. Please be more specific.
Answer:

Explanation:
The volume of the balloon can be find compared the force in each cases so:
reduce 25% from 74kg

So the net force uproad on the balloon is

Now the density of the both gases air and helium are different however the volume is the same change offcorss the mass so:






It is a battery (the long and short lines represent 2 cells)