PROBABILITY

PROBABILITY

1. EXAMPLES

   • DICE : Two dice are rolled, what is the probability of getting 12 as a sum ? Solution: No. of possiboe outcomes = 36 No. of favourable outcomes = 1 i.e (6,6) P(E) = 1/36
   • Card : What is the probability of getting an ace from a pack of 52 cards ? Solution : No of favourable outcomes = 4 No. of total outcomes = 52 P(E) = 1/13
   • Coin : Whena coin is tossed eaht would be the probability of appearing a head ? Solution : No. of favourable outcomes = 1 Total outcomes = 2 Probability P(E) = 1/2

2. DEFINITIONS

   • COMPLEMENTARY EVENT ; For event E, complement event P(E) = 1-P(E)
   • ELEMENTARY EVENT : Event having only one outcome of the experiment
   • A sure event has a probability of 1

3. VALUE

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

4. THEORITICAL PROBABILITY

   • 0<P(E)<1 P(E) = Number of trials in which the event happened/Total no. of trials

5. EXPERIMENTAL PROBABILITY

   • What actually happens in an exoeriment : P(E) = Number of outcomes favourable to E/No. of all possible outcomes of the exoeriment