Final Answer:
They rounded using the last number instead of the number just to the right of the spot to round.so the correct option is c).
Step-by-step explanation:
Rounding 80.13 to the nearest tens requires examining the digit in the tens place, which is the 8 in this case. The number just to the right of the tens place is 0.13. When rounding to the nearest tens, if the digit to the right is 5 or greater, the number in the tens place increases by 1; if it's less than 5, the number stays the same. In this instance, the student rounded using the last number, which is 0, instead of considering the number just to the right, which is 3. Thus, the correct rounded value should be 80, not 70.
To round a number to the nearest tens place, one needs to focus on the digit in the tens place. In the given number, 80.13, the digit in the tens place is 8. Rounding involves considering the digit immediately to the right of the place being rounded. In this case, it's the hundredths place (0.13). The rule for rounding is that if this digit is 5 or more, the number in the rounding place increases by 1; if it's less than 5, the number remains the same. The student incorrectly rounded down to 70, as they considered the last number, 0, instead of the number just to the right, which is 3.
In mathematical terms, the number 80.13 is between 80 and 90 on the number line. Rounding it to the nearest tens involves looking at the number's positioning between these values. Since 80.13 is closer to 80 than it is to 90, the correct rounded value should be 80. The digit to the immediate right of the tens place, the hundredths place, is 3, which is less than 5. Therefore, the digit in the tens place remains unchanged, resulting in 80 as the correct rounded value to the nearest tens. The student's mistake lies in not considering the digit in the hundredths place while rounding.