Probability of Being Sure

Tonight Tamara and I were at IKEA looking for kitchen ideas and I stumbled upon an interesting topic: I asked her, "What percent sure are you when you say you're 'reasonably sure'?" She said she's 85-95% sure. I then asked what percent sure she is when she says she's "pretty sure". She said 65-85% sure. I found that interesting because I am just the opposite. I'm more sure with pretty than with reasonably. Tamara thinks it has more to do with intonation than verbage.