Edward evaluates the expression 7.2 × 4.9 and gets an answer of 35.28.

Question

Is this a reasonable answer?
A.
Since 7.2 rounds to 7 and 4.9 rounds to 5, the multiplication rounds to 35. His answer of 35.28 rounds to 35, so it is reasonable.

B.
Since 7.2 rounds to 7 and 4.9 rounds to 5, the multiplication rounds to 35. His answer of 35.28 is not equal to 35, so it is not reasonable.

C.
Since 7.2 rounds to 8 and 4.9 rounds to 5, the multiplication rounds to 40. His answer of 35.28 is not equal to 40, so it is not reasonable.

D.
Since 7.2 rounds to 7 and 4.9 rounds to 4, the multiplication rounds to 28. His answer of 35.28 is not equal to 28, so it is not reasonable.

Answer 1

To evaluate whether Edward's answer of 35.28 for the expression 7.2 × 4.9 is reasonable, we can analyze the rounding options provided in the choices:

1. Choice A states that rounding 7.2 to 7 and 4.9 to 5 gives a multiplication result of 35. Since 35.28 rounds to 35, this means the answer is reasonable.

2. Choice B also uses the same rounding (7 to 7 and 5 to 5) but concludes that since 35.28 is not equal to 35, it is not reasonable. This is incorrect because a number close to 35 is still considered reasonable.

3. Choice C incorrectly rounds 7.2 to 8, which is not accurate. It suggests the product should be around 40, making it unreasonable, which is also incorrect since the initial roundings were not applied accurately.

4. Choice D rounds 4.9 inaccurately down to 4, which would lead to a product of 28, also concluding that the answer is unreasonable based on incorrect rounding.

The best analysis is provided by Choice A. Edward's final answer of 35.28 rounds to 35, which aligns closely with the expected value calculated from the rounded numbers (7 × 5 = 35).

Thus, the most reasonable choice is:

A. Since 7.2 rounds to 7 and 4.9 rounds to 5, the multiplication rounds to 35. His answer of 35.28 rounds to 35, so it is reasonable.