### Tips to Solve Problems on Probability

**Experiment : **An operation which can produce some well-defined outcomes is called an experiment.

**Random Experiment :**An experiment in which all possible outcomes are know and the exact output cannot be predicted in advance, is called a random experiment.

**Ex :**

i.Tossing a fair coin.

ii.Rolling an unbiased dice.

iii.Drawing a card from a pack of well-shuffled cards.

**Details of above experiments:**

i. When we throw a coin, then either a Head (H) or a Tail (T) appears.

ii. A dice is a solid cube, having 6 faces, marked 1, 2, 3, 4, 5, 6 respectively. When we throw a die, the outcome is the number that appears on its upper face.

iii. A pack of cards has 52 cards.

- It has 13 cards of each suit, name Spades, Clubs, Hearts and Diamonds.
- Cards of spades and clubs are black cards.
- Cards of hearts and diamonds are red cards.

There are 4 honours of each unit. There are Kings, Queens and Jacks. These are all called face cards.

**Sample Space: **When we perform an experiment, then the set S of all possible outcomes is called the sample space.

**Ex :**

i.In tossing a coin, S = {H, T}

ii.If two coins are tossed, the S = {HH, HT, TH, TT}.

iii.In rolling a dice, we have, S = {1, 2, 3, 4, 5, 6}.

**Event : **Any subset of a sample space is called an event.

**Probability of Occurrence of an Event : **

Let S be the sample and let E be an event.

Then,

**Results on Probability :**

i. P(S) = 1

ii.

iii.

iv. For any events A and B we have :

v. If denotes (not-A), then

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