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  • Question
  • A positive number when decreased by 4, is equal to 21 times the reciprocal of the number, the number?


  • Options
  • A. 3
  • B. 5
  • C. 7
  • D. 9

  • Correct Answer


  • Explanation

    Let the number be x,
    Then x - 4 = 21/x
    ? x2 - 4x - 21 = 0
    ? x2 - 7x + 3x - 21 = 0
    ? x(x - 7) + 3(x - 7) = 0
    ? (x - 7) (x + 3) = 0
    ? x = 7 (Neglecting = -3)


  • More questions

    • 1. 
      If a : b = 2 : 3 and 2 : a =1 : 2, then the value of 'b' is?

    • Options
    • A. 4
    • B. 6
    • C. 1 / 3
    • D. 3 / 2
    • Discuss
    • 2. 
      0.6 of a number equals 0.09 of another number. The ratio of the number is?

    • Options
    • A. 2 : 3
    • B. 1 : 15
    • C. 20 : 3
    • D. 3 : 20
    • Discuss
    • 3. 
      If a/3 = b/8, then ( a + 3 ) : ( b + 8 ) is equal to?

    • Options
    • A. 3 : 8
    • B. 8 : 3
    • C. 5 : 8
    • D. 3 : 5
    • Discuss
    • 4. 
      4, 19, 49,?, 229

    • Options
    • A. 75
    • B. 109
    • C. 65
    • D. 169
    • Discuss
    • 5. 
      777777 / 11 =?

    • Options
    • A. 7077
    • B. 70707
    • C. 7707
    • D. 7007
    • Discuss
    • 6. 
      Find the cardinal number of the following set {x: x is a natural number ? 30 and is divisible by 7 or 11}

    • Options
    • A. 4
    • B. 8
    • C. 6
    • D. 2
    • Discuss
    • 7. 
      SBI lent ? 1331 lakh to the TATA group at compound interest and got ?1728 lakh after 3 yr. What is the rate of interest charged, if compounded annually?

    • Options
    • A. 11%
    • B. 9.09%
    • C. 12%
    • D. 8.33%
    • Discuss
    • 8. 
      The sum of two numbers is 10. Their product is 20. Find the sum of the reciprocals of the two numbers.

    • Options
    • A. 1
    • B. 3/5
    • C. 1/2
    • D. 11//6
    • Discuss
    • 9. 
      5 men and 6 women can earn ? 2160 in 4 days. 8 men and 10 women can earn ? 4400 in 5 days. In how many days can 4 men and 9 women earn ? 1800?

    • Options
    • A. 3
    • B. 4
    • C. 5
    • D. 6
    • Discuss
    • 10. 
      A train 110 metres long travels at 60 km/hr. How long does it take to cross a telegraph post?

    • Options
    • A. 5 sec.
    • B. 5.6 sec
    • C. 6.6 sec
    • D. 6.8 sec
    • Discuss


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