Aptitude  Probability
Exercise : Probability  General Questions
 Probability  Formulas
 Probability  General Questions
11.
A card is drawn from a pack of 52 cards. The probability of getting a queen of club or a king of heart is:
Answer: Option
Explanation:
Here, n(S) = 52.
Let E = event of getting a queen of club or a king of heart.
Then, n(E) = 2.
P(E) =  n(E)  =  2  =  1  . 
n(S)  52  26 
12.
A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:
Answer: Option
Explanation:
Let S be the sample space.
Then, n(S)  = number of ways of drawing 3 balls out of 15  
= ^{15}C_{3}  


= 455. 
Let E = event of getting all the 3 red balls.
n(E) = ^{5}C_{3} = ^{5}C_{2} =  (5 x 4)  = 10. 
(2 x 1) 
P(E) =  n(E)  =  10  =  2  . 
n(S)  455  91 
13.
Two cards are drawn together from a pack of 52 cards. The probability that one is a spade and one is a heart, is:
Answer: Option
Explanation:
Let S be the sample space.
Then, n(S) = ^{52}C_{2} =  (52 x 51)  = 1326. 
(2 x 1) 
Let E = event of getting 1 spade and 1 heart.
n(E)  = number of ways of choosing 1 spade out of 13 and 1 heart out of 13 
= (^{13}C_{1} x ^{13}C_{1})  
= (13 x 13)  
= 169. 
P(E) =  n(E)  =  169  =  13  . 
n(S)  1326  102 
14.
One card is drawn at random from a pack of 52 cards. What is the probability that the card drawn is a face card (Jack, Queen and King only)?
Answer: Option
Explanation:
Clearly, there are 52 cards, out of which there are 12 face cards.
P (getting a face card) =  12  =  3  . 
52  13 
15.
A bag contains 6 black and 8 white balls. One ball is drawn at random. What is the probability that the ball drawn is white?
Answer: Option
Explanation:
Let number of balls = (6 + 8) = 14.
Number of white balls = 8.
P (drawing a white ball) =  8  =  4  . 
14  7 
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