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Quiz: Probability

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Number of Questions: 27

Question: 1 -

Two coins are thrown at the same time. Find the probability of getting both heads.

Options:

  1. 3/4

  2. 0

  3. 1/4

  4. 1/2

    5. Answer:

    1/4
    Solution:

    Since two coins are tossed, therefore total number of cases = 22 = 4

    Therefore, probability of getting heads in both coins is:

    ∴ P (head) = 1/4

Question: 2 -

A dice is thrown. Find the probability of getting an even number.

Options:

  1. 1

  2. 2/3

  3. 5/6

  4. 1/2

    5. Answer:

    1/2
    Solution:

    Total number of cases = 6 (1,2,3,4,5,6)

    There are three even numbers 2,4,6

    Therefore probability of getting an even number is:

    P (even) = 3/6

    ⇒ P (even) = 1/2

Question: 3 -

A bag contains 5 red balls and some blue balls .If the probability of drawing a blue ball is double that of a red ball, then the number of blue balls in a bag is:

Options:

  1. 20

  2. 10

  3. 15

  4. 5

    5. Answer:

    10
    Solution:

    Let the number of blue balls be x

    Then total number of balls will be 5 + x.

    According to question,

    x/(5 + x) = 2 X (5/5+x)

    ⇒ x = 10

Question: 4 -

Two dice are thrown simultaneously. The probability of getting a sum of 9 is:

Options:

  1. 1/9

  2. 1/10

  3. 4/9

  4. 3/10

    5. Answer:

    1/9
    Solution:

    Total cases = 36

    Total cases in which sum of 9 can be obtained are:

    (5, 4), (4, 5), (6, 3), (3, 6)

    ∴ P (9) = 4/36 = 1/9

Question: 5 -

100 cards are numbered from 1 to 100. Find the probability of getting a prime number.

Options:

  1. 3/4

  2. 1/4

  3. 29/100

  4. 27/50

    5. Answer:

    1/4
    Solution:

    Total prime numbers from 1 to 100 are:

    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

    That means 25 out of 100

    So probability is:

    P (prime) = 25/100

    ⇒ P (prime) = 1/4