The Probability Scale

Transcript

The Probability Scale Because probability is a measurement, it needs a scale. In math, we measure probability on a scale strictly from 0 to 1 We can think of it as a Number line or Percentage Some common events look like Impossible (0 or 0%): The event cannot logically happen. (e.g., Rolling a 7 on a standard 6-sided die) Less Likely (Between 0 and 0.5): The event can happen, but it probably won't. (e.g., Guessing answer of an MCQ with 4 options) Even Chance (0.5 or 50%): The event is just as likely to happen as it is to not happen. (e.g., Flipping heads on a coin) More Likely (Between 0.5 and 1): The event has a high probability of happening. (e.g., If a bag has 3 red marbles and 1 blue marble, reaching in blindly will very likely yield red.) Certain (1 or 100%): The event will absolutely, undoubtedly happen. (e.g., Sun rising tomorrow) Card example If we have 6 cards, the probability of picking a purple card changes depending on how many purple cards are actually in the deck More examples of Probability scale Some more examples of Probability Scale could be Event What it means Getting a number greater than 6 on a die Impossible: Dice only have numbers from 1 to 6. Rolling a 3 on a standard die Less likely: But not impossible as one face of the die is 3 . Flipping a coin and getting heads Even chance: Heads or tails are equally likely. Drawing any number from 2 to 10 from a deck of 52 cards More likely: There are 36 cards in a deck of 52 cards with numbers from 2 to 10. Choosing a red sweet from a bag of all red sweets Certain: All the sweets are red.