Final answer:
Without additional context, it's challenging to identify the exact error in Rosana's calculation of c being 225 inches. We need to consider if c represents the speed of light in which case the units would be incorrect, or if it's a length in a different context where the value and unit might be correct.
Step-by-step explanation:
To determine what needs to be corrected in Rosana's calculation that the length of c is 225 inches, it is important to understand the context of the problem. If c represents the speed of light, then the student may have made a mistake in the unit of measurement (inches) because the speed of light is a velocity usually expressed in units of meters per second (m/s). However, if c represents a length in a geometry or physics problem, then the number and unit might be plausible depending on the context.
The instructions point out that we need to be careful not to round off during the calculation and that we should check if the answer is reasonable. In physics, for instance with relativity problems, we should look out for velocities greater than c or relativistic effects in the wrong direction.
Given the information provided, we do not have enough context to determine the exact error in Rosana's calculation. However, common checks include ensuring that the value of c is correct, the unit of measurement is appropriate, the calculation method is accurate, and that rounding occurs only at the end of the problem.