Page 355 - Start Up Mathematics_8 (Non CCE)

AT a Glance

1. An experiment in which all possible outcomes are known but the exact outcome cannot be predicted in
advance is known as random experiment.
2. An event is one or more outcomes of a random experiment.
3. Performing a random experiment is called a trial.
4. An event obtained by combining two or more outcomes is called a compound event.
5. A collection of all possible outcomes of a random experiment is called sample space.
6. If there are n outcomes associated to a random experiment such that m of them are favourable to
Number of outcomes favourable to eventA
an event A, then probability of happening of A, i.e., P(A) = .
m Total numberof possibleouttcomes
\ P(A) =
n
7. For any event A, P(A) + P( A ) = 1.

Review Exercises

Multiple ChoiCe Questions
1. The collection of all possible outcomes of a random experiment is/are called:
(a) trials (b) events (c) sample space (d) probability
2. If a coin is tossed 3 times, the number of possible outcomes are:
(a) 8 (b) 6 (c) 10 (d) 4
3. Two fair dice are rolled simultaneously. The probability of getting the sum as 5 is:

(a) 1 (b) 2 (c) 1 (d) 4
6 3 9 9
4. In a pack of 52 cards, the number of face cards are:
(a) 3 (b) 6 (c) 9 (d) 12
5. If A denotes the happening of an event, then P( A ) is:
(a) 1 – P(A) (b) P(A) – 1 (c) 1 + P(A) (d) P(A)

solve Mentally

True or False
1. When a coin is tossed once, there are 4 outcomes.
2. The probability of an event lies between 0 and 1 (0 and 1 both inclusive).
3. An outcome of a random experiment is also an event.
2
4. The probability of getting an even number in one throw of a die is .
5. There are 4 suits in a pack of 52 cards. 5

Fill in the Blanks
1. Performing a random experiment is called a _____________.

2. For any event A, P(A) + P( A ) = _____________.
3. The number of outcomes in two throws of a die are _____________.
4. The probability of drawing a black card from a pack of 52 cards is _____________.
5. An event obtained by combining two or more sample points is called _____________.

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