Two resistors 5 ohm's each can be combined to give an equivalent resistance of​

10 Ω or 2.5 Ω

Explanation:

In series resistance R = 5 Ω + 5 Ω =10 Ω. If resistors are parallel, resistance is

1/R = 1/5Ω+ 1/5Ω and R = 2,5 Ω

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 =