Question 90

The student incorrectly placed the decimal in the answer.

The student's calculated sum of 4.5 and 0.923 is incorrect due to a misplacement of the decimal point in their final answer. Instead of arriving at the correct sum of 5.423, the student wrote 0.968, which indicates a decimal error.

A) Incorrectly placing the decimal in the answer

This option correctly identifies the student's error. The correct sum of 4.5 and 0.923 is 5.423, which shows that the student likely misplaced the decimal point when writing their answer, leading to a significant deviation from the actual sum.

B) Subtracting the numbers instead of adding

This option is incorrect because the student was tasked with adding the two numbers. There is no indication that subtraction occurred; the student attempted to add but made an error in placement, not in operation.

C) Adding digits that do not represent the same place value

While this may seem relevant, the student did not incorrectly add numbers of different place values. Instead, the student correctly attempted to add 4.5 and 0.923 but erred in placing the decimal in the resultant sum.

D) Making a regrouping error while adding

This option does not apply because regrouping typically refers to carrying over in addition, which is not relevant in this situation. The student's error was not related to regrouping but rather to the improper placement of the decimal in their final answer.

Conclusion

The student's incorrect placement of the decimal point in their answer is the primary error leading to the wrong result. All other options fail to accurately describe the nature of the mistake, as they pertain to different types of calculation errors that did not occur in this case. Therefore, option A most effectively explains the student's miscalculation.