Benchmark 12B
Habits of Mind: Computation and Estimation
Grades 6-8, page 291

Find what percentage one number is of another and figure any percentage of any number.

NSES Content Standard A 
Science as Inquiry: Abilities necessary to do scientific inquiry
Grades 5-8, page 148
Use mathematics in all aspects of scientific inquiry. Mathematics is essential to asking and answering questions about the natural world. Mathematics can be used to ask questions, to gather, organize and present data, and to structure convincing explanations.