logo

CuriousTab

CuriousTab

Discussion


Home Aptitude Odd Man Out and Series See What Others Are Saying!
  • Question
  • In a geometric progression, the sum of the first and the last terms is 66 and the product of the second and the last second terms is 128. Determine the first term of the series?


  • Options
  • A. 64
  • B. 64 or 2
  • C. 2 or 32
  • D. 32

  • Correct Answer
  • 64 or 2 

    Explanation

    Let a be the first term and and r be the common ratio of the GP. From the given problem,
    a + arn - 1 = 66 ...(i)
    Also, ar x arn - 2 = 128 ? a2rn - 1 = 128 ... (ii)
    From Eq. (ii),
    a.arn - 1 = 128
    arn - 1 = 128/ a
    On substitution this in Eq.(i), we get
    a + 128/a = 66
    a2 - 66a + 128 = 0
    a = [-b ± ?b2 - 4ac] /2a
    = 66 ± ?662 - 4 x 128 x 1)/2 = 64 or 2


  • More questions

    • 1. 
      The value of 47 / 10000 is?

    • Options
    • A. .0047
    • B. .0470
    • C. .00047
    • D. .000047
    • Discuss
    • 2. If 4x = 18y, then the value of ( x/y - 1) is

    • Options
    • A. 1 3
    • B. 7 2
    • C. 2 3
    • D. 3 2
    • Discuss
    • 3. 
      If the price of 23 toys is Rs. 276, then what will the price (Rs.) of 12 toys?

    • Options
    • A. 144
    • B. 158
    • C. 159
    • D. 166
    • Discuss
    • 4. 
      .02 =(......?.....)%

    • Options
    • A. 20
    • B. 2
    • C. .02
    • D. .2
    • Discuss
    • 5. 
      If 36 men can do a piece of work in 25 hours, in how many hours will 15 men do it?

    • Options
    • A. 45
    • B. 55
    • C. 60
    • D. 72
    • Discuss
    • 6. 
      2?63 / 11 =233

    • Options
    • A. 4
    • B. 3
    • C. 6
    • D. 5
    • Discuss
    • 7. 
      When 121012 is divided by 12, the remainder is

    • Options
    • A. 0
    • B. 2
    • C. 3
    • D. 4
    • Discuss
    • 8. 
      Aarti can do a piece of work in 6 days. In how many days will she complete three time of work of same type?

    • Options
    • A. 18 days
    • B. 21 days
    • C. 3 days
    • D. 6 days
    • Discuss
    • 9. 
      750.0003 ÷ 19.999 =?

    • Options
    • A. 49
    • B. 18
    • C. 22
    • D. 38
    • Discuss
    • 10. 
      105, 85, 60, 30, 0, - 45, - 90?

    • Options
    • A. 0
    • B. 85
    • C. -45
    • D. 60
    • Discuss


    Comments

    There are no comments.

Enter a new Comment