Sets and Functions


  1. In a group of 1000 people, there are 750 people who can speak Hindi and 400 who can speak English. How many can speak Hindi only?









  1. View Hint View Answer Discuss in Forum

    Given in the question,
    n(H ∪ E) = 1000, n(H) = 750, n(E) = 400
    Use the below formula,
    n(H ∪ E) = n(H) + n(E) – n(H ∩ E)

    Correct Option: A

    Given in the question,
    n(H ∪ E) = 1000, n(H) = 750, n(E) = 400
    Use the below formula,
    n(H ∪ E) = n(H) + n(E) – n(H ∩ E)
    We get 1000 = 750 + 400 – n(H ∩ E)
    ⇒ n(H ∩ E) = 1150 – 1000 = 150.
    Number of People who can speak Hindi only
    = n(H ∩ E′) = n(H) – n(H ∩ E)
    = 750 – 150 = 600.



  1. In a group of 70 people, 37 like coffee, 52 like tea and each person likes at least one of the two drinks. How many people like both coffee and tea?









  1. View Hint View Answer Discuss in Forum

    Let P = set of people who like coffee and Q = set of people like tea.
    Then, P ∪ Q = set of people who like at least one of the two drinks.
    And P ∩ Q = set of people who like both the drinks.

    Correct Option: A

    Let P = set of people who like coffee and Q = set of people like tea.
    Then, P ∪ Q = set of people who like at least one of the two drinks.
    And P ∩ Q = set of people who like both the drinks.
    Given in the question,
    n(P) = 37, n(Q) = 52, n(P ∪ Q) = 70.
    Use the below formula,
    n(P ∪ Q) = n(P) + n(Q) – n(P ∩ Q)
    Put the value from the given question,
    70 = 37 + 52 – n(P ∩ Q)
    ⇒ n(P ∩ Q) = 89 – 70 = 19.
    ∴ 19 people like both coffee and tea.



  1. In a town with a population of 5000, 3200 people are egg-eaters, 2500 meat eaters and 1500 eat both egg and meat. How many are pure vegetarians?









  1. View Hint View Answer Discuss in Forum

    Let, E be the set of people who are egg-eaters and M be the set of people who are meat-eaters.
    As per given question,
    n(E) = 3200, n(M) = 2500, n(E ∩ M) = 1500.
    Use the formula
    n(E ∪ M) = n(E) + n(M) – n(E ∩ M)

    Number of pure vegetarians = n(U) – n(E ∪ M)

    Correct Option: B

    Let, E be the set of people who are egg-eaters and M be the set of people who are meat-eaters.
    As per given question,
    n(E) = 3200, n(M) = 2500, n(E ∩ M) = 1500.
    Use the formula
    n(E ∪ M) = n(E) + n(M) – n(E ∩ M)
    = 3200 + 2500 – 1500
    = 5700 – 1500 = 4200.
    ∴ Number of pure vegetarians = n(U) – n(E ∪ M)
    Number of pure vegetarians = 5000 – 4200 = 800.



  1. If A = {a, d}, B = {b, c, e} and C = {b, c, f}, then A × (B ∪ C) =










  1. View Hint View Answer Discuss in Forum

    Given in the question,
    (B ∪ C) = {b, c, e} ∪ {b, c, f} = {b, c, e, f}
    ∴ A × (B ∪ C) = {a, d} × {b, c, e, f}

    Correct Option: C

    As per given question,
    (B ∪ C) = {b, c, e} ∪ {b, c, f} = {b, c, e, f}
    ∴ A × (B ∪ C) = {a, d} × {b, c, e, f}
    = {(a, b), (a, c), (a, e), (a, f), (d, b), (d, c), (d, e), (d, f)} …...........(1)
    Also, (A × B) = {(a, b), (a, c), (a, e), (d, b), (d, c), (d, e)}
    and, (A × C) = {(a, b), (a, c), (a, f), (d, b), (d, c), (d, f)} …............(2)
    ∴ (A × B) ∪ (A × C) = {(a, b), (a, c), (a, e), (a, f), (d, b), (d, c), (d, e), (d, f)}
    From (1) and (2), we have
    A × (B ∪ C) = (A × B) ∪ (A × C).



  1. If A and B are two sets such that A has 40 elements, A ∪ B has 60 elements and A ∪ B has 10 elements, how many elements does B have?









  1. View Hint View Answer Discuss in Forum

    Given in the question ,
    n(A) = 40, n(A ∩ B) = 60 and n(A ∩ B) = 10.
    Putting these values in the formula
    n(A ∪ B) = n(A) + n(B) – n(A ∩ B) we get
    60 = 40 + n(B) − 10
    ⇒ n(B) = 30.

    Correct Option: B

    Given in the question ,
    n(A) = 40, n(A ∩ B) = 60 and n(A ∩ B) = 10.
    As we know the formula,
    n(A ∪ B) = n(A) + n(B) – n(A ∩ B)
    Putting these values in the formula, we get
    60 = 40 + n(B) − 10
    ⇒ n(B) = 30.