📐
Chapter 9

Probability

MathematicsClass 12CBSE

44 Questions Available

Showing 20 questions on this page

1

A pair of dice is thrown. If the two numbers appearing on them are different, find the probability (i) the sum of the numbers is 6(ii) the sum of the numbers is 4 or less (iii) the sum of the number is 4.

148 views0 helpful
2

An electronic assembly consists of two sub-system, say A and B. From previous testing procedures, the following probabilities are assumed to be known.

P(A fails) = 0.2, P(B fails alone) = 0.15, P(A and B fail) = 0.15

Evaluate the following probabilities:

(i)  P(A fails/B has failed)              

(ii)  P (A fails alone)

134 views0 helpful
3

Two balls are drawn from an urn containing 2 white, 3 red and 4 black balls one by one without replacement. What is the probability that at least one balls is red?

117 views0 helpful
4

The odds against A solving a certain problem are 4 to 3 and the odds in favour of B solving the same problem are 7 to 5. Find the probability that the problem will be solved.

77 views0 helpful
5

Mother, father and son line up at random for a family picture. Find P(A/B), if A and B are defined as follows:

A = Son on one end, B = Father in the middle

73 views0 helpful
6

A die is thrown three times. Events A and B are defined as follows:

A: 4 on the third throw; B: 6 on the first and 5 on the second throw.

Find the probability of A given that B has already occurred.

70 views0 helpful
7

A couple has 2 children. Find the probability that both are boys, if it is known that (i) one of the children is a boy: (ii) the older child is a boy.

63 views0 helpful
8

A, B and C shot to hit a target. If A hits the target 4 times in 5 trials; B hits it 3 times in 4 trails and C hits 2 times in 3 trials; what is the probability that the target is hit by a least 2 persons?

62 views0 helpful
9

Three persons, A, B, C throw a die in succession till one gets a ‘six’ and wins the game. Find their respective probabilities of winning, if A begins.

61 views0 helpful
10

One bag contains 4 white and 5 black balls. Another bag contains 6 white and 7 black balls. A ball is transferred form first bag to the second bag and then a ball is drawn from the second bag. Find the probability that the ball drawn is white.

60 views0 helpful
11

Two persons A and B throw a die alternately till one of them gets a ‘three’ and wins the game. Find their respectively probabilities of wining, if A begins.

60 views0 helpful
12

The probabilities of A, B, C solving a problem are 1/3, 2/7 and 3/8 respectively. If all the three try to solve the problem simultaneously, find the probability that exactly one of them can solve it.

59 views0 helpful
13

In a bolt factory, machines A, B and C manufacture respectively, 25%, 35% and 40% of the total bolts. Of their output 5, 4, and 2 percent are respectively defective bolts. A bolt is drawn at random from the product. If the bolt drawn is found to be defective, what is the probability that it is manufactured by the machine B?

58 views0 helpful
14

A person has undertaken a construction job. The probabilities are 0.65 that there will be strike, 0.80 that the construction job will be completed on time if there is not strike, and 0.32 that the construction job will be  completed on time if there is a strike. Determine the probability that the construction job will be completed on time.

58 views0 helpful
15

A bag contains 4 red and 3 black balls. A second bag contains 2 red and 4 black balls. One bag is selected at random. From the selected bag, one ball is drawn. Find the probability that the ball drawn is red.

58 views0 helpful
16

A and B throw alternately a pair of dice. A wins if he throws 6 before B throws 7 and B wins if the throws 7 before A throws 6. Find their respective chance of winning, if A begins. 

57 views0 helpful
17

A speaks truth in 60% of the cases and B in 90% of the cases. In what percentage of cases are they likely to contradict each other in stating the same fact?

57 views0 helpful
18

A can hit a target 4 times in 5 shots, B 3 times in 4 shots, and C 2 times in 3 shots. Calculate the probability that 

(i) A, B, C all may hit   

(ii) B, C may hit and A may lose       

(iii) any two of A, B and C will hit the target.

(iv) none of them will hit the target.

56 views0 helpful
19

If each element of a second order determinant is either zero or one, what is the probability that the value of the determinant is positive? (Assuming that the individual entries of the determinant are chose independently, each value being assumed with probability 1/2).

56 views0 helpful
20

If each element of a second order determinant is either zero or one, what is the probability that the value of determinant is non-negative?

51 views0 helpful