I got this problem wrong on my quiz:

A 208.9 lb object displaces 2.73 gallons of water when submerged. What is the density of the object in g/L? (1 gal = 3.79 L, 1 kg = 2.20 lbs) Input your answer in scientific notation (use "E" for x10^, example: 1.0E2, you do not need units)

Selected Answer:

Incorrect 9.22E2

Correct Answer:

Correct 9.18E3 ± 5

What did I do wrong and what is the deal with the plus or minus 5 at the end of the correct answer?