The approximately correct answer range for this question was defined as anything between 65% and 75%. Only 15% of respondents answered this question with the exactly correct answer of 70%.
I'm sorry, no. Seventy percent is not "exactly correct". At best it is an estimate, and one that is subject to natural fluctuations due to things like temperatures, tidal patterns, etc.
How much should a layperson actually know about the planet's water coverage? "More than half water" is probably a little lacking; "between two-thirds and three-quarters" is probably about right.
"Between 70% and 71%" is worthless nitpicking, a rote recitation of a rule of thumb learned in grade school, the same place they learned that the speed of light is 186,000 miles per second, there are 2,000 pounds in a ton, and 1 yard = 1 meter.