Average


  1. Out of four number, the average of first three is 15 and that of the last three is 16, if the last number is 19, the first is ?









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    Sum of four number = ( 15 x 3 + 19 ) = 64
    Sum of last three number = ( 16 x 3 ) = 48
    ∴ first number = ( 64 – 48 ) = 16

    Correct Option: B

    Sum of four number = ( 15 x 3 + 19 ) = 64
    Sum of last three number = ( 16 x 3 ) = 48
    ∴ first number = ( 64 – 48 ) = 16


  1. The average temperature of the first three days is 27° C and that of the next three is 29° C . If the average of the whole week is 28.5° C, the temperature of the last day of the week is ?









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    Temperature of last day = Sum of temperature of 7 days - sum of temperature of first 6 days.

    Correct Option: C

    Temperature of last day = Sum of temperature of 7 days - sum of temperature of first 6 days.
    = ( 7 x 28.5 ) - [( 3 x 27 ) + ( 3 x 29 )]
    =31.5
    ∴ Temperature of last day = 31.5



  1. A ship sails out to a mark at the rate of 15 kmph. and sails back at the rate of 10 kmph. The average rate of sailing is ?









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    Average = ( 2uv / u +v ) km/hr

    Correct Option: B

    Average = ( 2uv / u +v ) km/hr
    = ( 2 x 15 x 10 ) / (15 +10 ) km/hr.
    = 12 km/hr.


  1. The average consumption of petrol for a car for seven months is 110 litres and for next five months it is 86 litres. The average monthly consumption is ?









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    Average = ( sum of consumption of petrol in first 7 months + sum of consumption of petrol in last 5 months. ) / 12

    Correct Option: C

    Average = ( sum of consumption of petrol in first 7 months + sum of consumption of petrol in last 5 months. ) / 12

    Average = ( 110 x 7 + 86 x 5 ) / 12
    =(1200 / 12 = 100 liters



  1. A batsman has a certain average runs for 11 innings . In the 12th innings he made a score of 90 runs and thereby decrease his average by 5 . His average after 12th innings is ?









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    Let the average for first 11 innings is y
    From question
    11y + 90 = (y - 5) x 12

    Correct Option: B

    Let the average for first 11 innings is y
    From question
    11y + 90 = (y - 5) x 12
    ⇒ y = 150
    ∴ Average after 12th inning = (150 - 5)= 145