Question

A sample obtained from the national bureau of standards had a calibrated weight of 20.000. When it was used tocalibrate a student's top loading balance, the balance showedthe following readings; 19.995, 20.005, 20.001. Comment onthe precision and accuracy of the balance.

Answer 1

Answer : The measurements are both precise and accurate.

Explanation :

Accuracy : It is defined as the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.

Precision : It is defined as the closeness of two or more measurements to each other.

For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.

Level of precision is determined by the maximum number of decimal places.

When the level of precision is very very less, the measurement can be considered as most precise and most accurate.

As we are given the standard value of the sample is 20.000 and the values measured by the balance are, 19.995, 20.005, 20.001.

Since these three values are in the range of +/- 0.005 from one another. So, we can say that the measurements are both precise and accurate.

Hence, the measurements are both precise and accurate.