Answer:
1 %
Explanation:
The efficiency of a system is defined as the ratio between the energy produced and the energy in input:
[tex]\eta = \frac{E_{out}}{E_{in}}\cdot 100[/tex]
The same formula can also be rewritten in terms of the power produced and the power in input:
[tex]\eta = \frac{P_{out}}{P_{in}}\cdot 100[/tex]
Since in this problem we have:
[tex]P_{in}=100 W\\P_{out}=1 W[/tex]
The efficiency is
[tex]\eta = \frac{1 W}{100 W}\cdot 100[/tex]=1 \%
