Question

You are given a cube of pure copper. You measure the sides of the cube to find the volume and weigh it to find its mass. When you calculate the density using your measurements, you get 8.78 grams/cm^3. Coppers accepted density is 8.96 g/cm^3. What is your percent error?

(a) 1%

(b) 0.02%

(c) 0.01%

(d) 2%

The question was asked in a job interview.

This interesting question is from Errors in Data and Calculations in division Presentation and Analysis of Data of Bioprocess Engineering

Answer 1

Correct option is (d) 2%

Easy explanation: Experimental value = 8.78 g/cm^3

Accepted value = 8.96 g/cm^3

Step 1: Subtract the accepted value from the experimental value.

8.78 g/cm^3 – 8.96 g/cm^3 = -0.18 g/cm^3

Step 2: Take the absolute value of step 1

|-0.18 g/cm^3| = 0.18 g/cm^3

Step 3: Divide that answer by the accepted value, 0.18g/cm^3 ÷ 8.96g/cm^3 = 0.02

Step 4: Multiply that answer by 100 and add the % symbol to express the answer as a percentage.

0.02 x 100 = 2

The percent error of your density calculation was 2%.