The hypothesis that left-handed persons form less than 10% of the total number of persons surveyed is proven to be true.
Left- handed persons live in right handed world. Almost all consumer items that are mass manufactured, are meant for a right- handed society. Basic tools and items like scissors, pliers, door knobs, buttons on a shirt, musical instruments and sports equipments are all designed and mass produced for the right handed majority. However left-hander takes pride in being part of the company of great minds including the likes of Leonardo da Vinci and Michelangelo!
Perhaps not all persons who are left-handed are also left-legged. Conduct another survey to find out how many left-handed persons kick ball with their left foot.
Conduct another survey on how many persons can fold their tongue.
Left-handedness - http://en.wikipedia.org/wiki/Left-handedness
Why are some people left-handed? - http://www.coolquiz.com/trivia/explain/docs/lefthand.asp