Probability from 0 to 1

1
Probability from 0 to 1

• 0 Impossible
• 1 Certain

2
Mathematical Probability

• Probability is a proportion
• P favorable outcomes / total outcomes
• You can show probability as a fraction, decimal
  or percentage
• P (2,4) d6 2 favorable/ 6 total 1/3 , 0.33, 33
• P (king) standard deck 4kings/52 cards 1/13,
  7.7
• Since probability is a fraction, it can never be
  greater than 1 or less than 0

3
Random

• To choose something (a number, a color, a name
  from a hat) blindly is to make a random choice.
• When you choose something randomly, no matter the
  probability, all outcomes are equally likely
• In a bag of MMs, if you take one without
  looking, no matter how many of each color is
  there, any one color is as likely as another.

4
Probability Scale

• Probability can be ranked along a scale from
  0 impossible, to 1 Certain

0 25 ½ 0.75
1 Impossible unlikely even likely
certain
5
Problem

• A deliveryman sends one newspaper to each of 1000
  houses.
• Thai Rat 100
• Manager Daily 250
• Thailand Daily 170
• Khom Chad Luek 130
• Matichon Daily 200
• Post Today 150
• If you choose randomly, what is the probability
  of a house having
• P (Matichon) P (Thai Rat or Post today), P (not
  Manager, or Thailand)