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  • Question
  • A man arranges to pay off a debt of ?3600 in 40 annual installments which form an Arithmetic Progression (A.P). When 30 of the installments are paid, he dies leaving one-third of the debt unpaid . Find the value of the first installment.


  • Options
  • A. 55
  • B. 53
  • C. 51
  • D. 49

  • Correct Answer
  • 51 

    Explanation

    Let us assume the first installment is a and difference between two consecutive installments is d.
    According to question,
    Sum of 40 Installments = 3600
    Apply the formula Sum of first n terms in an Arithmetic Progression = Sn = n/2[ 2a + (n?1)d ]
    where a = the first term, d = common difference, n = number of terms.

    n/2[ 2a + (n?1)d ] = 3600
    Put the value of a, n and d from question,
    40/2[ 2a + (40 ?1)d ] = 3600
    20[ 2a + 39d ] = 3600
    [ 2a + 39d ] = 3600/20 = 180
    2a + 39d = 180...........................(1)

    Again according to given question,
    After paying the 30 installments the unpaid amount = 1/3(total unpaid amount) = 3600 x 1/3
    After paying the 30 installments the unpaid amount = 1200
    So After paying the 30 installments the paid amount = 3600 - 1200 = 2400
    Sum of 30 installments = 2400
    30/2[ 2a + (30 ?1)d ] = 2400
    [ 2a + (30 ?1)d ] = 2400 x 2/30
    2a + 29d = 80 x 2 = 160
    2a + 29d = 160..........................(2)
    Subtract the Eq. (2) from Eq. (1), we will get
    2a + 39d - 2a - 29d = 180 - 160
    10d = 20
    d = 2
    Put the value of d in Equation (1), we will get
    2a + 39 x 2 = 180
    2a = 180 - 78
    a = 102/2
    a = 51
    The value of first installment = a = 51


  • More questions

    • 1. 
      A and B together can complete a work in 3 days. They started together but after 2 days, B left the work. If the work is completed after 2 more days, B alone could do the work in how many days?

    • Options
    • A. 5
    • B. 6
    • C. 7
    • D. 10
    • Discuss
    • 2. 
      A wheel makes 1000 revolutions in covering a distance of 88 km. the diameter of the wheel is?

    • Options
    • A. 24 meters
    • B. 40 meters
    • C. 28 meters
    • D. 14 meters
    • Discuss
    • 3. 25, 36, 49, 81, 121, 169, 225

    • Options
    • A. 36
    • B. 49
    • C. 121
    • D. 169
    • Discuss
    • 4. 
      (.896 x .752 +.896 x .248) / (.7 x .034 + .7 x.966) =?

    • Options
    • A. 1.28
    • B. 0.976
    • C. 12.8
    • D. 9.76
    • Discuss
    • 5. 
      Einstein goes from Ahmedabad To Lucknow at the speed of 40 km/hr and returned at the speed of 60 km/hr .the average speed of Einstein during the whole journey is

    • Options
    • A. 48 km/hr
    • B. 24 km/hr
    • C. 50 km/hr
    • D. none of these
    • Discuss
    • 6. 
      Today is Monday. After 61 days, it will be

    • Options
    • A. Wednesday
    • B. Saturday
    • C. Tuesday
    • D. Thursday
    • Discuss
    • 7. 9548 + 7314 = 8362 + (?)

    • Options
    • A. 8230
    • B. 8410
    • C. 8500
    • D. 8600
    • E. None of these
    • Discuss
    • 8. 
      The true discount on a certain sum due 1 yr hence at 30% per annum, is ? 240. What is the banker' discount on the same sum for the same time and at the same rate?

    • Options
    • A. ? 400
    • B. ? 212
    • C. ? 312
    • D. ? 445
    • Discuss
    • 9. 
      Calendar of month July is same as that of which month of previous year.

    • Options
    • A. May
    • B. September
    • C. April
    • D. None of these
    • Discuss
    • 10. 
      A coin is successively tossed two times. Find the probability of getting? (1) exactly one head (2)at least one head

    • Options
    • A. 1/2 , 3/4
    • B. 2/3, 1/4
    • C. 1/4, 4/5
    • D. 1/2, 2/3
    • Discuss


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