There are many possible orchestrations for this piano excerpt. This solution is much fuller than would normally be expected for this passage’s character, but we include it to provide an example of the types of things we look for in an orchestration excerpt. The critical factor is that you demonstrate knowledge of proper ranges, registers and transpositions of instruments; proper use or phrasing, articulations, dynamics, etc.; as well as an appropriate distribution of parts among the instruments of the orchestra.
For further study of scoring for orchestra, see:
Adler, Samuel. The Study of Orchestration. 3rd edition. W. W. Norton & Co.,
Specific study: Chapters 15, 17, & 18
Kennan, Kent and Donald Grantham. The Technique of Orchestration. 6th edition. Prentice Hall, 2002.
Specific study: Chapters 11, 16, 19 & 20