PROBABLITY

PROBABLITY

1. Definations

   • Elimentary Events Event having only one outcome of the experiment
   • Complementary Event For event E , complementary event, P(E)=1 - P(E)
   • Sure or Certain Event When event having probablity to occur as 1

2. Value

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

3. Experimental Probablity

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

4. Theoritical Probablity

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

5. Examples

   • Card What is the probablity 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
   • Coin When a coin is tossed , what would be the probablity of appearing head ? Solution : Total outcomes = 2 i.e. (H , T) Favourable outcomes =1 Required prob. P(E) + 1/2
   • Dice Two dice are rolled , What is probablity of getting 12 as a sum? Solution : Number of possible outcomes = 6^2 = 36 Number of favourable outcomes = 1 i.e. (6 , 6) P(E) = 1/36