You have two golf balls that differ only in their surfaces. One has dimples, while the other is smooth. If you were to drop the balls simultaneously from the top of the Eiffel-Tower, which will hit the ground first? a. Dimpled ball.
b. Smooth ball.
c. Both hit at the same time.
d. Whichever ball is heavier.

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 =