PROBABILITY

PROBABILITY

1. DEFINITION

   • SURE OR CERTAIN EVENTS When event having probability 1 to occur
   • COMPLEMENTARY EVENT For event E ,complementary event, P(E')=1-P(E)
   • ELEMENTARY EVENTS Event having only one outcome of the experiment

2. VALUE

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

3. EXPERIMENTAL PROBABILITY

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

4. THEORITICAL PROBABILITY

   • 0<P(E)<1
   • What we expect to happen in an experiment
   • P(E)=Number of trials in which the event happened/Total number of trials

5. EXAMPLE

   • COIN when coin is tossed , what would be the probability of appearing head? Solution : Total outcomes=2 Favourable outcomes=1 Req Prob. P(E)=1/2
   • CARDS: what is the probability of getting an ace from a pack of 52cards? Solution :Number of favourable outcomes=4 Number of possible outcomes=52 P(E)=4/52=1/13
   • DICE: Two dice are rolled what is the probability of getting 12 as a sum? Solution:Number of possible outcomes=36 Number of favourable outcomes=1 P(E)=1/36