Accuracy, Precision, and Percent Error Explained

The video tutorial explains the concepts of accuracy and precision, using examples like hitting a target and measuring the boiling point of water. It includes a practice section with targets to identify accuracy and precision levels. The tutorial analyzes student measurements of sodium chloride solubility, identifying which have high precision or accuracy. It also covers percent error, providing practice problems to calculate it, emphasizing the importance of expressing percent error as a positive value.

What is the definition of accuracy?

• The difference between the measured and accepted values

• The ability to hit the same spot repeatedly

• How close a series of measurements are to each other

• How close a measured value is to an accepted value

Which of the following is an example of high precision but low accuracy?

• Darts hitting the same region but far from the bullseye

• Darts hitting the bullseye and close together

• Darts scattered all over the target

• Darts hitting the bullseye but scattered

What does high precision indicate in an experiment?

• Measurements are close to the accepted value

• Measurements are close to each other

• Measurements are inaccurate

• Measurements are far from each other

Which student had high precision but low accuracy in their solubility measurements?

• Rowena

• None of the above

• Matthew

• Jordan

Which student had high precision and high accuracy in their solubility measurements?

• Jordan

• Matthew

• Rowena

• None of the above

What is the formula for calculating percent error?

• (Accepted value - Measured value) / Measured value * 100

• (Measured value - Accepted value) / Accepted value * 100

• (Accepted value - Measured value) / Accepted value * 100

• (Measured value - Accepted value) / Measured value * 100

If a student determined the boiling point of ethanol to be 70°C when the accepted value is 78°C, what is the percent error?

• 10.25%

• 8%

• 12.5%

• 10%

Calculate the percent error if a student determined the density of zinc to be 7.56 g/mL and the accepted value is 7.41 g/mL.

• 3.2%

• 1.5%

• 5.88%

• 2.02%

What is the accepted value for the density of aluminum according to reference table S?

• 2.7 g/cm³

• 2.8 g/cm³

• 2.6 g/cm³

• 2.5 g/cm³

If a student determined the density of aluminum to be 2.5 g/cm³, what is the percent error given the accepted value is 2.7 g/cm³?

• 8.2%

• 5.6%

• 6.3%

• 7.4%