SOME IMPORTANT QUESTIONS !!...

Q1. Find the probability that a leap year selected at random will contain 366 Sundays.

366 days = 52 weeks and 2 days.

therefore , leap year = 52 sundays.

the remaining two days can be :-

sunday and monday , monday and tuesday , tuesday and wednesday , wednesday and thursday ,
thursady and friday , friday and saturday , saturday and sunday.

total elementary events = 7 and favourable are 2

Therefore required probability = 2 / 7



Q2. Tickets numbered from 1 to 20 are mixed together . What is a probability that a ticket has
a number which is multiple of 3 or 7 ?

Here , total favourable outcomes = 3 , 6 , 7 , 9 , 12 , 14 , 15 and 18.

required probability = 8 / 20 = 2 / 5.



Q3. A bag contain 6oo pens out of which 12 are defective . What is probability for non - defective
pens ?

Total pens = 6oo
defective = 12
therefore , non - defective = 600 - 12 = 588

So , required probability = 588 / 600 = 49 / 50 = 0.98.



Q4. A letter is chosen at random from the letters of word 'ASSASSINATION' . Find the
probability that letter chosen is (i) vowel (ii) consonant.

Total letters = 13

(i) favourable for vowel = 6 (A , A , I , A , I , O )
SO , required probability = 6 / 13

(ii) probability for consonants = 1 - 6 / 13 = 7 / 13.



Q5. If x is chosen at random from the numbers -1 , 0 , 1 ,2 . What is a probability that x is
less than 2 ?

Total elementary outcomes = 5
favourable = 3 (-1 , 0 , 1)

So , required probability = 3 / 5.



Source :- R.D. Sharma and 100 % Success.

Feel free to ask about queries and clear your doubts !!!........