Probability CBSE Questions & Answers

Probability

This is Mathematics Class 11 Probability CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
A coin is tossed 6 times. The probability of getting a head three times is
  • A
    \({1 \over 2}\)
  • B
    \({1 \over 8}\)
  • C
    \({3 \over {64}}\)
  • D
    \({5 \over {16}}\)
    Correct
2
Five letters are sent to different persons and addresses on the five envelopes are written at random. The probability that all the letters reach correct destiny is
  • A
    \({1 \over 5}\)
  • B
    \({{44} \over {120}}\)
  • C
    \({1 \over {120}}\)
    Correct
  • D
    none of these
3
The letters are sent to different persons and addresses on the three envelopes are written at random. The chance that none of the letters reaches correct destiny is
  • A
    0
  • B
    none of these
  • C
    \({2 \over 3}\)
  • D
    \({1 \over 3}\)
    Correct
4
A pack of cards contain 4 aces, 4 kings, 4 queens and 4 jacks. Two cards are drawn at random. The probability that atleast one of them is a king is
  • A
    \({1 \over 9}\)
  • B
    \({3 \over {16}}\)
  • C
    \({1 \over 5}\)
  • D
    \({9 \over {20}}\)
    Correct
5
A number of five digits is formed by using the digits 0, 1, 2, 3, 4, no digit being repeated in any number. The probability that it is a number divisible by 4 is
  • A
    \({1 \over 4}\)
  • B
    \({4 \over {15}}\)
  • C
    \({5 \over {16}}\)
    Correct
  • D
    \({1 \over 3}\)
6
From each of the four married couples, one of the partners is selected at random. The probability that those selected are of the same sex is
  • A
    \({1 \over 4}\)
  • B
    \({1 \over 8}\)
    Correct
  • C
    \({1 \over {16}}\)
  • D
    \({1 \over 2}\)
7
The probability of having atleast one tail in 4 throws with a coin is
  • A
    \({1 \over {16}}\)
  • B
    \({{15} \over {16}}\)
    Correct
  • C
    1
  • D
    \({1 \over 4}\)
8
The letters of the word ‘PROPBABILITY’ are arranged in all possible ways. The chance that two B’s and also two I’s occur together is
  • A
    none of these
  • B
    \({2 \over {55}}\)
    Correct
  • C
    \({1 \over {55}}\)
  • D
    \({4 \over {165}}\)
9
Two persons A and B appear in an interview for two vacancies. If the probabilities of their selection are \({1 \over 4}\) and \({1 \over 6}\) respectively, then the probability that none of them is selected is
  • A
    \({5 \over 8}\)
    Correct
  • B
    \({{19} \over {12}}\)
  • C
    \({1 \over {24}}\)
  • D
    \({5 \over {12}}\)
10
A fair coin is tossed n times and let X denotes the number of heads obtained. If P (X = 4), P (X = 5) and P (X = 6) are in A.P., then n is equal to
  • A
    14
  • B
    7 or 14
    Correct
  • C
    none of these
  • D
    7
11
A seven digit number is formed by using the digits 1, 2, 3, 4, 5, 6, 7, 8, 9 ; no digit being repeated in any number. The probability that the number so formed is a multiple of 9 is
  • A
    \({1 \over 3}\)
  • B
    \({1 \over 9}\)
    Correct
  • C
    \({2 \over 9}\)
  • D
    \({1 \over 5}\)
12
A sum of money is rounded off to the nearest rupee. The probability that the error occurred in rounding off is atleast 15 paise is
  • A
    \({{29} \over {100}}\)
  • B
    \({{29} \over {101}}\)
  • C
    \({{71} \over {101}}\)
  • D
    \({{71} \over {100}}\)
    Correct
13
Three numbers are chosen at random from 1 to 20. The probability that they are consecutive is
  • A
    \({3 \over {190}}\)
    Correct
  • B
    none of these
  • C
    \({1 \over {60}}\)
  • D
    \({1 \over {57}}\)
14
A positive integer is chosen at random. The probability that sum of the digits of its square is 39 is
  • A
    0
    Correct
  • B
    \({2 \over {39}}\)
  • C
    0
  • D
    \({1 \over {11}}\)
15
A class consists of 80 students, 25 of them are girls and 55 boys. If 10 of them are rich and the remaining poor and also 20 of them are intelligent and others are not, then probability of selecting an intelligent rich girl is
  • A
    none of these
  • B
    \({5 \over {512}}\)
    Correct
  • C
    \({5 \over {128}}\)
  • D
    \({{25} \over {128}}\)