Average


  1. Columbus started his journey from Lucknow to Kolkata, Which is 200 K.M., at the speed of 40 KM/hr, then he went to Banglore which is 300 Km, at the speed of 20 KM/hr . Further he went to Ahmedabad which is 500 Km, at the speed of 10 Km/hr. The average speed of Columbus is :









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    Average speed = Total distance/Total time

    Correct Option: A

    Total distance = (200 + 300 + 500) = 1000
    Total time = 200/40 + 300/20 + 500/10 = 5 + 15 + 50 = 70 hr

    Average speed = Total distance / Total time =1000 / 70 = 14.2857 Km/hr.


  1. If the algebraic sum of deviations of 20 observation measured from 23 is 70, mean of these observation would be











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    Mean = (sum of observation) / (number of observation)

    Correct Option: E

    Mean = (sum of observation) / (number of observation)
    Sum of observation is given as = 70
    Number of observation = 20
    ∴ Mean = 70/20 = 3.5
    But, here observation starts from= 23.
    ∴ Mean = 23 + 3.5 = 26.5



  1. The average of 50 number is 38. If the two numbers 45 and 55 are not considered, What will be the average of remaining numbers?









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    According to the basic formula of average,
    Average(A)= Sum (S) / Number(N)
    ∴ 38 = S/50
    ∵ S = 38 x 50 = 1900

    Sum of remaining number after eliminating 45 and 55
    = 1900 - (45 + 55) = 1800

    Average of remaining numbers = (Sum of remaining number) / (Remaining number)

    Correct Option: C

    According to the basic formula of average,
    Average(A)= Sum (S) / Number(N)
    ∴ 38 = S/50
    ∵ S = 38 x 50 = 1900

    Sum of remaining number after eliminating 45 and 55
    = 1900 - (45 + 55) = 1800

    Average of remaining numbers = (Sum of remaining number) / (Remaining number)
    = 1800 / ( 50 - 2)
    = 1800/48
    = 37.5


  1. The average marks of 30 students are 45 but after checking there are two mistakes found. After adjustment if a student got 45 more markes and other student got 15 less marks, then What will be the adjusted average?









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    Total number of all students of the class = 30 x 45 = 1350
    ∴ New average after adjustment = (1350 - 45 + 15)/30

    Correct Option: B

    Total number of all students of the class = 30 x 45 = 1350
    ∴ New average after adjustment = (1350 - 45 + 15)/30 = 1320/30 = 44



  1. The mean marks obtained by seven students group is 226. If the marks obtained by six of them are 340, 180, 260, 56, 275 and 307 respectively. Find the markes obtained by the seventh student.









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    ∴ Marks obtained by seventh students
    = Total marks of seven students - Total marks of the six student

    Correct Option: A

    Sum of marks of 7 students = Mean x Number of students
    = 226 x 7 = 1582

    Now, total marks of 6 students = (340 + 180 + 260 + 56 + 275 + 307) = 1418

    ∴ Marks obtained by seventh students
    = Total marks of seven students - Total marks of the six student
    = 1582 - 1418
    = 164