The distance between two consecutive nodes of a standing wave is 21.9 cm. the hand generating the pulses moves up and down through a complete cycle 2.13 times every 3.65 s. find the velocity of the wave. answer in units of m/s.

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 =