FUTURE MAP 2025-2045: Discover the Crucial Trends Consumer Brands Must Act on to Prosper in this Massively Transformation Era. See that here.

This is a Quora question I was asked and here is my answer.

That will depend on additional data.

Do a search for a sample size calculator and you will probably see a lot of options where you can plug in your assumptions to give you the minimum sample size needed.

Optimizely has a quick and easy one, here, as does Survey Monkey, here.