Q5 of 8 Page 307

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

Here sample space consist of 26 alphabets. So total number of possible outcomes = 26


Out of these a, e, i , o and u are vowels , ∴ number of vowels are 5


And remaining 21 alphabets are consonants.


a) let E be the event of drawing a vowel


then, P (E) =


b) There are q, r, s ,t , u, v, w , x ,y, z alphabets which comes after letter P.


The number of alphabets to come after p = 10


And let F be the event of drawing a letter which comes after P


P (F) =


(c) Since English alphabets consist of vowels or a consonant


The possibility of drawing a vowel or a consonant will be sum of probability of both the events happening equally likely


⇒


Which is also the probability of a sure event.


(d) the consonant in English alphabets are b, c, d , f, g, h, , j , k ,l , m ,n, p, q , r ,s ,t ,v, w, x, y, z


The number of consonant are = 21


Let E be the event of drawing a consonant


Then P ( E) =


More from this chapter

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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.

 6

Eleven bags of wheat flour, each marked 5 kg, actually contained the following weights of flour (in kg):

4.97, 5.05, 5.08, 5.03, 5.00, 5.06, 5.08, 4.98, 5.04, 5.07, 5.00


Find the probability that any of these bags chosen at random contains more than 5 kg of flour.

 7

An insurance company selected 2000 drivers at random (i.e., without any preference of one driver over another) in a particular city to find a relationship between age and accidents. The data obtained is given in the following table:


Find the probabilities of the following events for a driver chosen at random from the city:


i. The driver being in the age group 18-29 years and having exactly 3 accidents in one year.


ii. The driver being in the age group of 30-50 years and having one or more accidents in a year.


iii. Having no accidents in the year.