To determine what error Noah may have made, we need to clarify the steps involved in finding the median of a set of numbers:
- Order the numbers from smallest to largest (if they are not already in order).
- If there is an odd number of values, the median is the middle number.
- If there is an even number of values, the median is the average of the two middle numbers.
Given the options available and without the actual numbers that Noah worked with, the most common errors in calculating the median usually relate to ordering the numbers or incorrectly pairing them when trying to find the median.
Here are the possible errors listed in the responses:
- He forgot to put the numbers in order first. – This is a common error since the median calculation requires sorted input.
- He did not make any error. – This would mean he followed all steps correctly.
- He crossed off the high/low number pairs incorrectly. – This suggests mistakes in eliminating numbers, which could lead to errors in finding the correct median.
- He left out a number when putting the numbers in order. – This is also a possible mistake that would affect the result.
Without knowing Noah's specific work, it’s difficult to definitively identify his error. However, if the problem involved misordering or missing numbers, the first two responses (especially the first one) are likely candidates for the error type.
If we were to choose based on typical issues encountered, "He forgot to put the numbers in order first." would be the most reasonable response if we assume intervention has not been made to check the order of numbers before calculation.