Question

If 20,000J of energy is available to plants, how much energy is available to man in:

Plant - Sheep - man?

Answer 1

Applying 10% rule....
The energy available to man will be 10% of energy available to sheep

energy to sheep- 10/100 * 20,000=2000J

energy to man- 10/100 * 2000=200J

Answer 2

By 10% Law of Nature.

We have 20000 Joules of Energy available for plants

Therefore, Sheep will have 10% of 20000 Joules of Energy

=> 20000 × $\frac{1\cancel{0}}{10\cancel{0}}$

=>$2000\cancel{0}\times\:\frac{1}{1\cancel{0}}$

=> 2000 Joules of Energy for sheeps.

=> For man, It will have, 10% of 2000 Joules of Energy.

=>2000 × $\frac{1\cancel{0}}{10\cancel{0}}$

=>$200\cancel{0}\times\:\frac{1}{1\cancel{0}}$

=> 200 Joules of Energy.

Hence, The final answer is

$\boxed{200\:Joules\:of\: Energy}$