A couple of years ago i posted a running total of my roll up the rim to win coffee purchases. i wanted to see if the 1 in 9 chance would actually occur in my own purchases, while also being aware of the geographical inconsistencies in which Tim Hortons distributes its winning cups. This allowed my students and i to engage in conversations around a real-life example of probability. It was fun, (and it may actually resulted in a few coffees being purchased FOR me by some students and their parents — wink, wink.) So i will continue this practice on the Six Nations Numeracy blog this year. Tim Hortons claims a 1 in 6 chance of winning this year, as they have added more prizes.
However, one factor i didn’t anticipate that may have “skewed” the results, were those instances where i actually purchased the coffee, but as a gift for someone else. Did those winning cups count towards my total? Is that why my actual buying experience didn’t concur with Tim Hortons’ alleged odds? So this year, i will include any winning cups i bought for others. Maybe good karma has its way of working and messing with probability?
Drinks for me: 23
Drinks for others: 6
Drinks for me, purchased by others: 4
Total Drinks Purchased: 33
Winning cups for me: 2
Winning cups for others: 2
Winning cups for me, purchased by others: 0
Total winning cups: 4
Odds for me: 2 in 23
Odds for others: 2 in 6
Odds for me, purchased by others: 0 in 4
Total odds: 4 in 33