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Aptitude miscellaneous
  1. The average of 20 numbers is calculated as 35. It is discovered later on that while calculating the average, one number, namely 85, was mis read as 45. The correct average is :








  1. View Hint View Answer Discuss in Forum

    Here , The average of 20 numbers = 35
    Sum of 20 numbers = 20 × 35
    According to question ,
    Correct sum of 20 numbers = 20 × 35 – 45 + 85
    Correct sum of 20 numbers = 700 + 40 = 740

    Correct Option: C

    Here , The average of 20 numbers = 35
    Sum of 20 numbers = 20 × 35
    According to question ,
    Correct sum of 20 numbers = 20 × 35 – 45 + 85
    Correct sum of 20 numbers = 700 + 40 = 740

    ∴ Required average =
    740
    		 = 37
    20

  1. The average marks of a class of 35 children is 35. The marks of one of the students, who got 35, was incorrectly entered as 65. What is the correct average of the class?








  1. View Hint View Answer Discuss in Forum

    According to question ,
    Total correct marks of 35 children = 35 × 35 + 35 – 65 = 1225 – 30 = 1195

    Required average =
    1195
    		 = 34.14
    35

    Second method to find the required average ,
    Diffference = – 65 + 35 = – 30

    Correct Option: B

    According to question ,
    Total correct marks of 35 children = 35 × 35 + 35 – 65 = 1225 – 30 = 1195

    Required average =
    1195
    		 = 34.14
    35

    Second method to find the required average ,
    Diffference = – 65 + 35 = – 30
    Required average = 35 –
    30
    35

    Required average = 35 – 0.857 = 34.143

  1. The average weight of 15 oarsmen in a boat is increased by 1.6 kg when one of the crew, who weighs 42 kg is replaced by a new man. Find the weight of the new man (in kg).








  1. View Hint View Answer Discuss in Forum

    Here, N = 15, T = 42, t = 1.6
    We can find required answer with the help of given formula ,
    Weight of new oarsman = ( N + T × t )
    Weight of new oarsman = (42 + 15 × 1.6) kg.

    Correct Option: C

    Here, N = 15, T = 42, t = 1.6
    We can find required answer with the help of given formula ,
    Weight of new oarsman = ( N + T × t )
    Weight of new oarsman = (42 + 15 × 1.6) kg.
    ∴ Weight of new oarsman = (42 + 24) kg. = 66 kg.

  1. The average of 10 numbers is 7. If each number is multiplied by 12, then the average of the new set of numbers will be








  1. View Hint View Answer Discuss in Forum

    As we know that If each number is multiplied by a certain number, then the average is also multiplied by that number.
    Given , The average of 10 numbers = 7

    Correct Option: D

    As we know that If each number is multiplied by a certain number, then the average is also multiplied by that number.
    Given , The average of 10 numbers = 7
    ∴ Required average = 7 × 12 = 84

  1. The average weight of five persons sitting in a boat is 38 kg. The average weight of the boat and the persons sitting in the boat is 52 kg. What is the weight of the boat ?








  1. View Hint View Answer Discuss in Forum

    Given that , The average weight of five persons sitting in a boat = 38 kg.
    Sum of weight of five persons = 5 × 38 = 190
    The average weight of the boat and the persons sitting in the boat = 52 kg.
    Sum of weight of the boat and five persons = 6 × 52 = 312

    Correct Option: B

    Given that , The average weight of five persons sitting in a boat = 38 kg.
    Sum of weight of five persons = 5 × 38 = 190
    The average weight of the boat and the persons sitting in the boat = 52 kg.
    Sum of weight of the boat and five persons = 6 × 52 = 312
    ∴ Weight of the boat = Sum of weight of the boat and five persons – Sum of weight of five persons
    Weight of the boat = 312 – 190 = 122 kg