Average


  1. A cricketer whose bowling average is 12.4 runs per wicket, takes 5 wickets for 26 runs and thereby decreases his average by 0.4. The number of wickets taken by him till the last match was









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    Let required number of wickets = n
    According to question,
    ⇒ 12.4 × n + 26 = (n + 5) (12.4 – 0.4)
    ⇒ 12.4 × n + 26 = (n + 5) × 12
    ⇒ 12.4n + 26 = 12n + 60
    ⇒ 12.4n – 12n = 60 – 26
    ⇒ 0.4n = 34

    Correct Option: D

    Let required number of wickets = n
    According to question,
    ⇒ 12.4 × n + 26 = (n + 5) (12.4 – 0.4)
    ⇒ 12.4 × n + 26 = (n + 5) × 12
    ⇒ 12.4n + 26 = 12n + 60
    ⇒ 12.4n – 12n = 60 – 26
    ⇒ 0.4n = 34
    ⇒ n = 34 ÷ 0.4

    ∴ n =
    340
    = 85
    4


  1. The average of 9 observations was found to be 35. Later on, it was detected that an observation 81 was misread as 18. The correct average of the observations is :









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    Given that , The average of 9 observations = 35
    Later on, it was detected that an observation 81 was misread as 18 .
    Correct sum of 9 observations = 9 × 35 – 18 + 81
    Correct sum of 9 observations = 315 + 63 = 378

    Correct Option: B

    Given that , The average of 9 observations = 35
    Later on, it was detected that an observation 81 was misread as 18 .
    Correct sum of 9 observations = 9 × 35 – 18 + 81
    Correct sum of 9 observations = 315 + 63 = 378
    ∴ Required correct average = 378 ÷ 9 = 42



  1. The average of runs of a cricket player of 10 innings was 32. How many runs must he make in his next inning so as to increase his average of runs by 4 ?









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    Let the batsman make p runs.
    Total runs in 10 innings = 10 × 32 = 320

    320 + p
    = 32 + 4
    11

    ⇒ 320 + p = 36 × 11
    ⇒ p = 396 – 320 = 76
    Second method to solve this question with the help of given formula :
    Here, T = 32, N = 11, t = 4

    Correct Option: A

    Let the batsman make p runs.
    Total runs in 10 innings = 10 × 32 = 320

    320 + p
    = 32 + 4
    11

    ⇒ 320 + p = 36 × 11
    ⇒ p = 396 – 320 = 76
    Second method to solve this question with the help of given formula :
    Here, T = 32, N = 11, t = 4
    Required Run = T + Nt [Here N is taken as (n + 1)]
    Required Run = 32 + 11 × 4
    Required Run = 32 + 44 = 76


  1. A cricket player after playing 10 tests scored 100 runs in the 11th test. As a result, the average of his runs is increased by 5. The present average of runs is









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    Here , A cricket player after playing 10 tests scored in the 11th match = 100 runs
    If the average in 10 tests be n , then
    According to question ,
    ⇒ n × 10 + 100 = (n + 5) × 11
    ⇒ 11n – 10n = 100 – 55

    Correct Option: C

    Here , A cricket player after playing 10 tests scored in the 11th match = 100 runs
    If the average in 10 tests be n , then
    According to question ,
    ⇒ n × 10 + 100 = (n + 5) × 11
    ⇒ 11n – 10n = 100 – 55
    ⇒ n = 45
    ∴ Required average = 50



  1. A student, by mistake, wrote 64 in place of 46 as a number at the time of finding the average of 10 given numbers and got the average as 50. The correct average of the numbers is :









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    Here , Average of 10 given numbers = 50
    A student, by mistake, wrote 64 in place of 46 , then
    Correct sum of numbers = 10 × 50 – 64 + 46
    Correct sum of numbers = 500 – 18 = 482

    Correct Option: A

    Here , Average of 10 given numbers = 50
    A student, by mistake, wrote 64 in place of 46 , then
    Correct sum of numbers = 10 × 50 – 64 + 46
    Correct sum of numbers = 500 – 18 = 482
    ∴ Correct average = 482 ÷ 10 = 48.2