Q1 of 8 Page 307

A die has six faces numbered from 1 to 6. It is rolled and number on the top face is noted. When this is treated as a random trial.

a) What are the possible outcomes?


b) Are they equally likely? Why?


c) Find the probability of a composite number turning up on the top face.

Here the sample space consist of outcomes = 1,2,3,4,5 and 6


Number of possible outcomes = 6


a) As sample space consist of all possible outcomes,


S (possible outcomes ) = 1,2,3,4,5 and 6


b) Yes, since every number (face) has equal possibility of coming up in a random trial they are equally likely. The possibility of each number is .


c) let E be the event of composite number turning up


the possible outcomes are 4 and 6


number of possible outcomes = 2


probability of a composite number turning up is =



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2

A coin is tossed 100 times and the following outcomes are recorded

Head:45 times


Tails:55 times from the experiment


a) Compute the probability of each outcomes.


b) Find the sum of probabilities of all outcomes.

 3

A spinner has four colours as shown in the figure. When we spin it once, find

a) At which colour, is the pointer more likely to stop?


b) At which colour, is the pointer less likely to stop?


c) At which colours, is the pointer equally likely to stop?


d) What is the chance the pointer will stop on white?


e) Is there any colour at which the pointer certainly stops?


 4

A bag contains five green marbles, three blue marbles, two red marbles, and two yellow marbles. One marble is drawn out randomly.

a) Are the four different colour outcomes equally likely? Explain.


b) Find the probability of drawing each colour marble i.e. , P(green), P(blue), P(red) and P(yellow)


c) Find the sum of their probabilities.

 5

A letter is chosen from English alphabet. Find the probability of the letters being

a) A vowel


b) a letter comes after P


c) A vowel or a consonant


d) Not a vowel