PROBABILITY

PROBABILITY

1. Value

   • Sum of probabilities of all elementary events is 1. For events A,B,C ; P(A) + P(B) + P(C) = 1

2. Experimental probability

   • What actually happens in an experiment number of outcomes P(E)= favourable to E/ number of all possible outcomes of the experiment

3. Theoretical probability

   • 0<P(E)<1 What we expect to happen in an experiment Number of trials in P(E) = which of the event happened / Total no. of trials

4. Definitions

   • Elementary event having only one outcomes of the experiment
   • Complementary event for event E, complementary event, P(E) = 1, P(E)
   • Sure or certain event when event having probability to occur as 1

5. Examples

   • DICE: Two dice are rolled , what is the probability of getting 12 as a sum ? solution: Number of possible outcomes = 6*6 = 36. Number of favourable outcomes = 1 i,e, (6,6) P(E) = 1/36
   • COIN: When a coin is tossed, what would be the probability of appearing head? SOLUTION: Total outcomes = 2 i.e, (H,T) Fvourable outcomes = 1 P(E) = 1/2
   • CARD: What is the probability of getting an ace from a pack of 52 cards? SOLUTION; Number of favourable outcomes =4 Number of possible outcomes = 52 P(E) = 4/52 = 1/13