Final answer:
To estimate the product of 11.45×5, we round 11.45 down to 11 and multiply by 5 to get an estimate of 55. This estimate is an underestimate since the exact product is slightly more.
Step-by-step explanation:
To estimate the product of 11.45×5 using rounding, we should first round 11.45 to the nearest whole number. 11.45 is closer to 11 than to 12, so we round it down to 11. Next, we multiply 11 by 5, which gives us 55. Therefore, the estimated product is 55. Since the actual product of 11.45×5 would be slightly more than 55 because 11.45 is greater than 11, our estimate is an underestimate.
The correct answer is A. 55, underestimate.