Answer:
The most accurate measurement is 2.829 cm.
Explanation:
We can round the decimals to a certain accuracy in order to make further calculations easier.To round a number to the nearest hundredth ,check the next place value to the right (the thousandths). If it's less than 5, remove all the digits to the right. If the place value is 5 or greater than 5, just add 1 to the previous digit (the hundredths place digit) and drop all other digits to the right.
In other words, to round off a decimal number, the procedure is as follows; if the digit to the right of the required number is a 5 or greater, add 1 to previous digit and drop all the remaining digits. If the required number is less than 5, do not change the previous digit and remove all the remaining digits.
Here, a piece of metal with a length of 2.83 cm was measured using four different devices. The obtained measurements are 2.837 cm, 2.829 cm, 2.812 cm and 2.805 cm.
Thus, the first measurement 2.837 cm can be round off to 2.84 cm. The second measurement 2.829 cm can be round off to 2.83 cm. The third measurement 2.812 cm can be round off to 2.81 cm and the fourth measurement 2.805 cm can be round off to 2.81 cm.
So the most accurate measurement is the second one, 2.829 cm which can be round off to 2.83 cm.
