Jing has 1200 ft2 of roof in his home in pittsburgh, pa (hdd = 6,000). he is considering upgrading the insulation from r-16 to r-22. the estimate from the contractor was $554. his home is heated with natural gas. last year, the average price he paid for natural gas was $14.6/mcf. assuming an afue of 84.1%, how long will it take jing to recover his investment?

1/0.14nm = 10^10/1.4 a lot

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 =