IIT JEE प्रश्न और उत्तर का अभ्यास करें

प्र: In an objective competitive exam, a correct answer score 4 marks and on a wrong answer 2 marks are negatively added. A student scores 420 marks from 150 question. How many answers were correct ? 4330 0

  • 1
    145
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  • 2
    138
    सही
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  • 3
    125
    सही
    गलत
  • 4
    120
    सही
    गलत
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उत्तर : 4. "120"
व्याख्या :

Answer: D) 120 Explanation: let x be the correct answer and y be the wrong answerso the total number of questions is (x + y) = 150.....(1)=> 4x - 2y = 420.....(2)By solving (1) & (2), we get => 6x = 720hence x = 120Therefore, number of correct answers are 120.

प्र: Find the missing number in the given number series? 2676, 445, ?, 21,6, 2, 1 4326 0

  • 1
    88
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  • 2
    92
    सही
    गलत
  • 3
    96
    सही
    गलत
  • 4
    102
    सही
    गलत
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उत्तर : 1. "88"
व्याख्या :

Answer: A) 88 Explanation: The given number series 2676, 445, ?, 21,6, 2, 1 follows a pattern that, From right side, 1 1 x 1 + 1 = 2 2 x 2 + 2 = 6 6 x 3 + 3 = 21 21 x 4 + 4 = 88 88 x 5 + 5 = 445 445 x 6 + 6 = 2676   Hence the missing number in the given number series is 88.

प्र: There are three rooms in a Hotel: one single, one double and one for four persons. How many ways are there to house seven persons in these rooms ? 4319 0

  • 1
    105
    सही
    गलत
  • 2
    7! x 6!
    सही
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  • 3
    7!/5!
    सही
    गलत
  • 4
    420
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उत्तर : 1. "105"
व्याख्या :

Answer: A) 105 Explanation: Choose 1 person for the single room & from the remaining choose 2 for the double room & from the remaining choose 4 people for the four person room,   Then, 7C1 x 6C2 x 4C4  = 7 x 15 x 1 = 105

प्र: P is faster than Q. P and Q each walk 24 km. The sum of their speeds is 7 km/hr and the sum of times taken by them is 14 hours. Then, P's speed is equal to ? 4316 0

  • 1
    3 km/hr
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  • 2
    4 km/hr
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    गलत
  • 3
    5 km/hr
    सही
    गलत
  • 4
    6 km/hr
    सही
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उत्तर : 2. "4 km/hr"
व्याख्या :

Answer: B) 4 km/hr Explanation: Let P's speed = x km/hr. Then, Q's speed = (7 - x) km/ hr.   So, 24/x + 24/(7 - x) = 14   x2 - 98x + 168 = 0   (x - 3)(x - 4) = 0 => x = 3 or 4.   Since, P is faster than Q,   so P's speed = 4 km/hr and Q's speed = 3 km/hr.

प्र: There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was : 4297 0

  • 1
    20
    सही
    गलत
  • 2
    35
    सही
    गलत
  • 3
    54
    सही
    गलत
  • 4
    40
    सही
    गलत
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उत्तर : 1. "20"
व्याख्या :

Answer: A) 20 Explanation: Numbers of students in section A = x ∴ Numbers of students in section B and C = (100 – x) ∴ x 70 + (100 – x) 87.5 = 84 100 => 70x + 87.5 100 – 87.5x = 8400 => 8750 – 17.5x = 8400 => 17.5x = 8750 – 8400 => x = 20.

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उत्तर :
व्याख्या :

Answer 1) True Answer 2) Cannot tell Answer 3) True

प्र: Raju got married 8years ago. His present age is 6/5 times his age at the time of his marriage  Raju's sister was 10years younger to him at the time of his marriage. The present age of Raju's sister is  ? 4295 0

  • 1
    30
    सही
    गलत
  • 2
    32
    सही
    गलत
  • 3
    38
    सही
    गलत
  • 4
    None
    सही
    गलत
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उत्तर : 3. "38"
व्याख्या :

Answer: C) 38 Explanation: Let Raju's age at the time of his marriage = X years Then from given data => X + 8 = 6/5 X X = 40. Since got married 8 years ago, his present age  = 48 His sister is 10 years younger => 48 - 10 = 38 years.

प्र: A company requires 12,100 strength. Present employees are 400 ladies and 6400 gents. To reach the target how many ladies required to maintain the same ratio ? 4290 0

  • 1
    400
    सही
    गलत
  • 2
    600
    सही
    गलत
  • 3
    900
    सही
    गलत
  • 4
    700
    सही
    गलत
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उत्तर : 3. "900"
व्याख्या :

Answer: C) 900 Explanation: 6,400 gents, 2400 ladies in that company.So total 8,800employees.for 8,800 employees, we want 2400 ladies.for 12,100employees we want how many ladies ?=> (12,100/8,800) x 2400 = 3300.So we want 3300 - 2400 = 900 more ladies.

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