(c) The loudness (perceived volume by the human ear) of a sound of d decibels doubles each time the intensity of a sound increases by a factor of ten. To the human ear, how many times louder does a 120-decibel sound seem than a 80-decibel sound

b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =