Answer: 27,27%
Percent error is experimental value error divided by the actual value. To answer this question you need to know how much experimental value error in this case. You just need to find the difference in estimate with the actual weight. It should be 13.75 pounds- 10 pounds= 3.75 pounds.
After that, you need to divide the experimental value error with the actual value. The calculation would be: 3.75 pounds/ 13.75 pounds x 100%= 27,27%
