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Aptitude miscellaneous
  1. The average age of 30 students of a class is 14 years 4 months. After admission of 5 new students in the class the average becomes 13 years 9 months. The youngest one of the five new students is 9 years 11 months old. The average age of the remaining 4 new students is








  1. View Hint View Answer Discuss in Forum

    Given that , The average age of 30 students = 14 years 4 months.
    Total age of initial 30 students = 14 years 4 months × 30 = 430 years
    After admission of 5 new students, the average of 35 students = 13 years 9 months.
    Total age of 35 students = 13 years 9 months × 35
    Total age of 35 students = (455 + 26) years 3 months = 481 years 3 months
    ∴ Total age of 4 new students = 481 years 3 months – 430 years – 9 years 11 months = 481 years 3 months – 439 years 11 months
    Total age of 4 new students = 41 years 4 months

    Correct Option: A

    Given that , The average age of 30 students = 14 years 4 months.
    Total age of initial 30 students = 14 years 4 months × 30 = 430 years
    After admission of 5 new students, the average of 35 students = 13 years 9 months.
    Total age of 35 students = 13 years 9 months × 35
    Total age of 35 students = (455 + 26) years 3 months = 481 years 3 months
    ∴ Total age of 4 new students = 481 years 3 months – 430 years – 9 years 11 months = 481 years 3 months – 439 years 11 months
    Total age of 4 new students = 41 years 4 months

    ∴ Required average = 41 years 4 months
    4

    Required average = 10 years 4 months

  1. The average age of P, Q and R is 5 years more than R’s age. If the total ages of P and Q together is 39 years, then R’s age is








  1. View Hint View Answer Discuss in Forum

    According to question,

    ⇒ P + Q + R = R + 5
    3

    ⇒ P + Q + R = 3R + 15
    ⇒ P + Q = 3R – R + 15
    ⇒ 2R + 15 = P + Q = 39
    ⇒ 2R = 39 – 15 = 24

    Correct Option: A

    According to question,

    ⇒ P + Q + R = R + 5
    3

    ⇒ P + Q + R = 3R + 15
    ⇒ P + Q = 3R – R + 15
    ⇒ 2R + 15 = P + Q = 39
    ⇒ 2R = 39 – 15 = 24
    ⇒ R = 24 ÷ 2 = 12 years
    Hence , R’s age is 12 years .

  1. Three years ago the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family remains the same today. The age of the baby today is








  1. View Hint View Answer Discuss in Forum

    Three years ago , the average age of 5 members = 17 years.
    Total age of 5 member family 3 years ago = 17 × 5 = 85 years
    Their total present age = 85 + 3 × 5 = 100 years
    Born on new baby , the average age of 6 members remain same . i.e. 17 years
    Total present age of 6 members = 17 × 6 = 102 years
    ∴ Present age of child = Total present age of 6 members - Total present age of 5 members

    Correct Option: B

    Three years ago , the average age of 5 members = 17 years.
    Total age of 5 member family 3 years ago = 17 × 5 = 85 years
    Their total present age = 85 + 3 × 5 = 100 years
    Born on new baby , the average age of 6 members remain same . i.e. 17 years
    Total present age of 6 members = 17 × 6 = 102 years
    ∴ Present age of child = Total present age of 6 members - Total present age of 5 members
    Hence , Present age of child = 102 – 100 = 2 years

  1. 3 years ago the average age of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is








  1. View Hint View Answer Discuss in Forum

    Given , Five years ago, average age of five members = 17 years
    Five years ago, total age of five members = 17 × 5 = 85 years
    Sum of their present ages = 85 + 3 × 5 = 100 years
    Born on new baby , average age of 6 members = 17 years
    Sum of present ages of 6 members = 17 × 6 = 102 years

    Correct Option: C

    Given , Five years ago, average age of five members = 17 years
    Five years ago, total age of five members = 17 × 5 = 85 years
    Sum of their present ages = 85 + 3 × 5 = 100 years
    Born on new baby , average age of 6 members = 17 years
    Sum of present ages of 6 members = 17 × 6 = 102 years
    ∴ Present age of baby = 102 – 100 = 2 years

  1. If out of 10 selected students for an examination, 3 were of 20 years, age, 4 of 21 and 3 of 22 years, the average age of the group is








  1. View Hint View Answer Discuss in Forum

    As per the given details in question ,

    Average age of the whole group = 3 × 20 + 4 × 21 + 3× 22
    10

    Average age of the whole group = 60 + 84 + 66
    10

    Correct Option: B

    As per the given details in question ,

    Average age of the whole group = 3 × 20 + 4 × 21 + 3× 22
    10

    Average age of the whole group = 60 + 84 + 66
    10

    Average age of the whole group = 210
    10

    Hence , Average age of the whole group = 21 years