Friday, 19 February 2016

CBSE Class 10 - Maths - 5 Minutes Revision of Probability

Probability


5 Minutes Revision



1. The sample space of an experiment is the set of all possible outcomes of the experiment.


2. The sample space when a coin is tossed three times is

     S  = {HHH, HHT, HTH, HTT, THH, THT, TTH, TTT}


3. Basic formula to find Probability of an event (E) is

Number of Favourable Outcomes
P(E) =  divided by
Total Number of Outcomes


4. An event that is not very likely has a probability close to 0.


5. An event that is very likely has a probability close to 1 (100%).


6. If probability of happening an event is x then probability of not happening that event is (1-x).


7. If probability of winning a game is 0.6 then probability of loosing it is (1-0.6) = 0.4



8. If probability of finding a broken piece in a factory is 2 out of 7 i.e. 2/7 then probability of finding a unbroken item is (1-2/7) = 5/7


9. When a probability is based on data gathered from an experiment, it is called an experimental probability or an empirical probability


10. In a deck of playing cards, there are four types of cards :

   ♠ (Spades in Black colour) having A, 2,3,4,5,6,7,8,9,10,J,K, and Q total 13 cards
   ♣ (Clubs in Black colour) having A, 2,3,4,5,6,7,8,9,10,J,K, and Q total 13 cards
   ♥ (Hearts in Red colour) having A, 2,3,4,5,6,7,8,9,10,J,K, and Q total 13 cards
   ♦ (Diamond in Red colour) having A, 2,3,4,5,6,7,8,9,10,J,K, and Q total 13 cards


11. Total cards = 52 cards


12. Jack, King and Queen are known as ‘Face Cards’ , As these cards are having some pictures on it.


13. Note that Ace is not a 'face card' as it doesn’t carry any face on it.


14. If one coin is tossed the total number of outcomes are 2 either a Head or a Tail.


15. If two coins are tossed the total number of outcomes are 2 × 2 = 4


16. If three coins are tossed the total number of outcomes are 2 ×2×2 = 8


17. Similarly for Dice, In a single roll total number of outcomes are 6


18. If two Dices are rolled, total number of outcomes are 6×6 = 36


19. Two events A and B are mutually exclusive if they cannot occur at the same time.


20. If A and B are two mutually exclusive events, then the probability of A or B written
      P (A or B) = P(A) + P(B)





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