Question

A tertiary consumer, such as a red-tailed hawk, receives what percent of the energy fixed by primary producers in a typical field ecosystem?

Answer 1

Assuming a 10% trophic efficiency, the herbivore (primary consumer) will get 10% of the producer energy. Then, the second consumer that eat the herbivore will get 10% of the primary consumer energy, so it is 10%*10%= 1% of the primary producers.
Then, the tertiary consumer should get 0.1% of the primary producers' energy.

Answer 2

Since only 10 percent of energy obtained in one trophic level is successfully passed to the next trophic level in the case of the tertiary consumer ( the organism that is in the third trophic level) the organism will obtain only 1 percent of the initial energy.
For example, a plant would obtain the energy from the radiation of the sun, 10% of that will be passed to a field mouse that eats the plant, and the 10% of the 10% or 1% of the initial energy would be obtained by the hawk.