Biruk wants to buy a book for $15.25 and a book for $4.85. He wants to pay with one $20.00 bill. Use estimation to decide whether this is reasonable or not. Explain what place value to round for an estimate this is useful in this situation.
This is reasonable because $15.25 rounds to $20.00, and $4.85 rounds to $5.00. Added up, that would equal $25.00, which is pretty close to $20.00.
To estimate whether it is reasonable for Biruk to pay for the books with a $20.00 bill, we can round the prices to the nearest whole number. This means we'll round the price of the book that costs $15.25 to $15.00 and the price of the book that costs $4.85 to $5.00.
By rounding to the nearest whole number, we are effectively ignoring the decimal places and focusing on the place value of the whole number. This is useful in this situation because it gives us a quick approximation and helps us determine whether the total cost is close to the amount Biruk has or not.
Now, let's add the rounded prices together:
$15.00 + $5.00 = $20.00
When we add the rounded prices, the total comes out to be exactly $20.00. This indicates that the estimated total is equal to the amount Biruk has, which means it is reasonable for him to pay for the books with a $20.00 bill.
However, it's important to note that this estimation is based on rounding, so the actual total cost may differ slightly from the estimate. If Biruk wants a more precise calculation, he should consider using the exact values of $15.25 and $4.85.