Actually, here is the correct answer. The person above (but if I get brainliest, the person below) me didn't answer the question properly. He/she just talked about estimation not how you could use estimation to check the reasonableness of a solution to a practical problem.
Usually, when you try and solve a problem, you estimate first. After that, you actually solve the problem to get the exact answer. If your estimate was close to your answer, it probably means that your answer is correct. For example, take a look at this problem: Miguel must always have at least $500 in his bank savings account to avoid a fee charged by the bank. He has $764 in the account. He wants to withdraw $278 from the account. Miguel believes that he will not be charged a fee if he makes this withdrawal. Estimate with lower or upper bound estimate to see if he is correct. Notice that the problem uses the word “at least”. These words tell you to find a lower bound estimate. Miguel’s balance can never be less than 500 dollars. The lower bound estimate in subtraction is the result of rounding the minuend down and the subtrahend up. If the lower bound estimate is equal to, or less than five hundred dollars then Miguel may risk having an actual balance less than five hundred dollars after the withdraw. The lower bound estimate equals four hundred dollars. Since the estimate is less than five hundred dollars, Miguel’s balance could drop below five hundred dollars if he withdraws two hundred seventy-eight dollars. So Miguel should re-think his conclusion. In fact if he withdraws two hundred seventy eight dollars his actual balance would be four hundred eighty-six dollars. So he would be charged a fee.
I turned this in and got 100% on K12. It was for my math journal. I didn't copy. Search it on a plagiarism website if you think I did.
