Question

The volume of liquid is 26 ml . A student measures the volume and finds is to be 26.2 ml ,26.1 ml ,25.9 ml respectively. Which of the following statement is true for his measurements
a)They are neither precise nor accurate
b)They have poor accuracy
c)They have good precision
d)They have poor precision ​

Answer 1

According to the given data,-"They have poor precision" - this statement is true(Option - d)

• For calculating the value, mostly 3 observations are collected and the mean of the 3 values is the result.
• Mean is defined as the sum of all the values(observations or measurements)/number of total observations.
• Sum of observations = 26.2 + 26.1 + 25.9 = 78.2
• number of observations = 3
• Mean = 78.2/3
• Mean = 26.0
• Therefore, the mean i.e. 26 matches the true value i.e. 26ml, hence, the result is accurate and the accuracy is good.
• Accuracy is defined as the closeness of measured value to the true/given value.
• Precision is the closeness between the measured values i.e how much closer is the first observation to the second observation.
• more the closeness between the observations- more is the precision.
• The readings or observations should be reproducible for good precision.
• 26.2 ≠ 26.1 ≠ 25.9

Hence, the measurements or observations were not repeated, therefore the measurements have poor precision.