George evaluates the expression on a trivia quiz.

Question

-8.13/2 1/10+12

He gets an answer of 8.88. Is this a reasonable answer?
A.
Since -8.13 rounds to -8 and rounds to 2, the final answer rounds to 8.
His answer of 8.88 rounds to 9. So, it is not reasonable.

B.
Since -8.13 rounds to -8 and rounds to 2, the final answer rounds to 9.
His answer of 8.88 rounds to 8. So, it is not reasonable.

C.
Since -8.13 rounds to -9 and rounds to 3, the final answer rounds to 10.
His answer of 8.88 rounds to 9. So, it is not reasonable.

D.
Since -8.13 rounds to -9 and rounds to 3, the final answer rounds to 9.
His answer of 8.88 rounds to 9. So, it is reasonable.

Answer 1

To evaluate George's answer, we first need to compute the expression:

\[ -8.13 / 2.1 + 12 \]

Calculating \(-8.13 / 2.1\):

\[ -8.13 \div 2.1 \approx -3.867619 \]

Now, adding \(12\):

\[ -3.867619 + 12 \approx 8.13238 \]

Thus, the final answer is approximately \(8.13\).

Now, let's analyze the rounding options:

1. Rounding \(-8.13\) gives us \(-8\).
2. Rounding \(2.1\) gives us \(2\).

So when calculating using the rounded values:

\[ -8 / 2 + 12 = -4 + 12 = 8 \]

Next, let's compare the final answers based on rounding:

• The calculated answer \(8.13\) rounds to \(8\).
• George's answer \(8.88\) rounds to \(9\).

Now let's evaluate the provided options:

• A: His answer of 8.88 rounds to 9. So, it is not reasonable. → This statement is correct.
• B: His answer of 8.88 rounds to 8. So, it is not reasonable. → This statement is incorrect.
• C: His answer of 8.88 rounds to 9. So, it is not reasonable. → This statement is correct but the reasoning is wrong since the final considers rounding to 8.
• D: His answer of 8.88 rounds to 9. So, it is reasonable. → This statement is incorrect.

Thus, the conclusion correct and reasonable should be option A, because the rounded value of the final answer is \(8\), while George’s answer of \(8.88\) rounds to \(9\), which is not reasonable.