Average


  1. The average weight of 19 students is 15kg. by the admission of a new student the average weight is reduced to 14.8 kg. the weight of the new student is ?









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    Weight of new student = Total weight of all 20 students - Total weight of initial 19 students
    = (20 x 14.8 - 19 x 15) kg

    Correct Option: C

    Weight of new student = Total weight of all 20 students - Total weight of initial 19 students
    = (20 x 14.8 - 19 x 15) kg
    = 11 kg.


  1. The average weight of 8 persons is increased by 2.5 kg, when one of them whose weight is 56 kg is replaced by a new man. The weight of the man is ?









  1. View Hint View Answer Discuss in Forum

    Total Increase = 8 x 2.5 = 20 kg.

    Correct Option: C

    Total Increase = 8 x 2.5 = 20 kg.
    weight of new man = (56 + 20) kg = 76 kg



  1. The average of the daily income of A, B and C is Rs . 60 . If B earns Rs . 20 more than C and A earns double of what C earns. What is the daily income of C ?









  1. View Hint View Answer Discuss in Forum

    Let C's earning = Rs. y.
    Then, B's earning = Rs. (y + 20)
    and A's earning = Rs. 2y
    From question 2y + y + 20 + y= 3 x 60

    Correct Option: C

    Let C's earning = Rs. y.
    Then, B's earning = Rs. (y + 20)
    and A's earning = Rs. 2y
    ∵ 2y + y + 20 + y= 3 x 60
    ⇒ 4x = 160
    ∴ x = 40


  1. The average age of an adult class is 40 years. 12 new students with an average age of 32 years join the class. Therefore decreasing the average by 4 year. what was the original strength of class ?









  1. View Hint View Answer Discuss in Forum

    Let original strength = y
    Then , 40y + 12 x 32 = ( y + 12) x 36

    Correct Option: C

    Let original strength = y
    Then , 40y + 12 x 32 = ( y + 12) x 36
    ⇒ 40y + 384 = 36y + 432
    ⇒ 4y = 48
    ∴ y = 12



  1. In a class, there are 20 boys whose average age is decreased by 2 months, when one boy aged 18 years is replaced by a new boy. The age of the new boy is ?









  1. View Hint View Answer Discuss in Forum

    Total decrease
    = ( 20 X 2 ) months
    = 3 years 4 month

    ∴ Age of the new boy
    = ( 18 years ) – ( 3 years 4 months)

    Correct Option: A

    Total decrease
    = ( 20 X 2 ) months
    = 3 years 4 month
    ∴ Age of the new boy
    = ( 18 years ) – ( 3 years 4 months)
    = 14 years 8 month