CBSE - Probability

1 Probability 

 A bag contains 10 red balls and some white balls. If the probability of drawing a white ball is double that of a red ball, then number of white balls in the bag will be 
 
1) 10
2) 15
3) 20 
4) 25 

2 Probability 

Two cards are drawn together from a pack of 52 cards. The probability that one is  a spade and other is a heart, is :    
 
1) 3 / 20
2) 29 / 34
3) 47 / 100
4) 13 / 102 

3 Probability 

The probability of guessing the correct answer to a certain question is p/12. If the probability of not guessing the correct answer to the same question is 3/4, the value of p is  
 
1) 3
2) 4
3) 2
4) 1

4 Probability 

There are 50 cards maked with the numbers 1 to 50. One card is drawn at random. What is the probability that number on the card is a prime number ?

1) 3 /10
2) 1 / 5
3) 1 / 4
4) 2 /15

5 Probability 

A die is thrown twice. The probability of the sum being odd, is
 
1) 1 / 2
2) 1 / 3
3) 1 / 4
4) 1 / 6 

6 Probability 

Out of a day’s production, which is 1000 machine  parts, 100 we re  found to be  sub-standard. The  probability that a part se le cte d at random be ing up to the  standard is
 
1) 1 / 10
2) 9 / 10
3) 2 / 10
4) 5 / 10

7 Probability 

In a class, there are 15 boys and 10 girls. Three students are selected at random. The probability that 1 girl and 2 boys are selected, is: 
 
1) 21 / 46
2) 25 / 117
3) 1 / 50
4) 3 / 25 

8 Probability 

Box A contains 30% first grade articles. Box B contains 40% first grade articles. One article is draw from each box. Then the probability that both articles drawn are first grade is   
 
1) 1 / 25
2) 3 / 25
3) 7 / 25 
4) 9 / 25 

9 Probability 

Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5? 
1)  1 / 2
2)  2 / 5
3)  8/ 15
4) 9 / 20
 

10 Probability 

In a single throw of three dice, the probability of getting a total of 17 or 18 is 
 
1) 53/54
2) 51/54
3) 1/54 
4) 0