Quantitative Aptitude: Simple/Compound Interest Set 09

Simple Interest/Compound Interest Questions for IBPS PO, SBI PO, NIACL, NICL, LIC, UICL, Bank of Baroda and other competitive exams.

1. A sum of amount at r% compound interest doubles in 2 years. In 6years it will be a times of the original principal. What is the value of r?
   A) 8
   B) 6
   C) 10
   D) 12
   E) None
   
   View Answer

   Option A
   Solution:
   A=P(1+r/100)ⁿ
   2P=P(1+r/100)²
   2=(1+r/100)²
   Take both side cube , it become 6 years
   2³ = { (1+r/100)² } ³
   8= { (1+r/100)⁶ }.
2. Rs 15000 amounts to Rs 25920 in 3 years at r% per annum of compound interest. What is the value of r?
   A) 10
   B) 15
   C) 20
   D) 12
   E) None
   
   View Answer

   Option C
   Solution:
   A=P(1+r/100)ⁿ
   25920=15000(1+r/100) ³
   25920/15000 = (1+r/100) ³
   648/375 = (100+r) ³/100³
   Put r value from options
   R=20%.
3. If simple interest on a certain sum of money for 6 years at 5% per annum is same as the simple interest on Rs. 720 for 8 years at the rate of 6% per annum then the sum of money is
   A) Rs 1152
   B) Rs 1235
   C) Rs 1310
   D) Rs 1420
   E) None
   
   View Answer

   Option A
   Solution:
   X *6*5/100 = 720*8*6/100
   X = 144*8 ==> 1152.
4. Harish borrowed a sum of money and returned it in three equal quarterly installment of Rs17576 each. Find the sum borrowed if the rate of interest charged was 16% per annum compounded quarterly . find also the total interest charged?
   A) 36425, 3215
   B) 48775, 3953
   C) 45620, 3542
   D) 38565, 2965
   E) None
   
   View Answer

   Option B
   Solution:
   Rate of Interest = 16% per annum
   Actual rate of Interest = 4% per Quarter
   Principal of all three installments
   =17576 [(1+4/100) +(1+4/100)² +(1+4/100)³]
   = [ 17576 (25/26) + (25/26)² + (25/26)³]
   =[17576*25*1951/26*676] = 48775
   Total amount paid = Rs.17576 *3 = 52728
   Interest charged = 52728 – 48775 = 3953.
5. Mr. X invested 1/4 of his total investment at 5% and 1/3 at 4% and rest at 3% for the one year and received total interest of Rs. 460. What is the total sum invested?
   A) Rs 14000
   B) Rs 13500
   C) Rs 15000
   D) Rs 12000
   E) None
   
   View Answer

   Option D
   Solution:
   Let the Principal be x, then
   [ (x/4)*5 + (x/3)*4 + (5x/12)*3]/100 = 460
   X= Rs 12000.
6. A person invests some amount at 4% per annum and another amount at 6% per annum. If two-third of the first amount is equal to the one-two of the second amount, and total interest earned in 2 years is Rs. 1080, what was the total sum invested?
   A) Rs10500
   B) Rs8950
   C) Rs 9365
   D) Rs 10125
   E) None
   
   View Answer

   Option A
   Solution:
   Let the first amount be ‘x’ and the second amount be ‘y’
   (2/3)*x = (1/2)*y
   x = 3/4y
   Total interest earned in 2 years = 1080
   (x*4*2)/100 + (y*6*2)/100 = 1080
   (3/4y*4*2) /100 + (12y)/100=1080
   18y=1080*100
   Y=6000.
   Then , x = 3/4y = 4500
   Therefore, total sum invested = 6000+4500 = Rs.10500.
7. An amount is invested in two schemes, A and B. Ratio of investment in A to that of B is 17:8. A gives interest after 2 years at 10% compound interest while B gives interest after 2 years at 21% simple interest. What will be the ratio of interest earned through A to that of B?
   A) 9:11
   B) 17:16
   C) 14:11
   D) 16:13
   E) None
   
   View Answer

   Option B
   Solution:
   Amount invested in A = 17x
   Amount invested in B = 8x
   Interest earned through A = (17x)*[(1+10/100)² -1 ]
   =(17x*2100)/10000=(17x*21)/100
   Interest earned through B = [(8x)*(21)*2]/100
   Required ratio = (17x*21)/100 : (8x*21*2)/100= 17 : 16.
8. Find the amount of Rs. 5000 invested at 10% during the period from 1st Jan, 2017 to 15 Apr 2017
   A) Rs 4935.25
   B) Rs 5345.5
   C) Rs 5200
   D) Rs 5143.8
   E) None
   
   View Answer

   Option D
   Solution:
   Jan 31 Feb 28 March 31 April 15
   Time Period =31+28+31+15 =105days =105/365 years
   Amount= 5000 + (5000*10*105)/ 100*365 = 5000 + 143.8
   =5143.8.
9. A sum is being lent at 15 % per annum compound interest what is the ratio of increase in amount of 4th year to 5th year?
   A) 12:17
   B) 20:23
   C) 13:19
   D) 23:19
   E) None
   
   View Answer

   Option B
   Solution:
   P(1+15/100)⁴/ P(1+15/100)⁵
   =1/ (1+15/100)=1/(115/100)=100/115
   20:23.
10. At what percent per annum will a sum of money triple in 14 years?
    A) 13%
    B) 15%
    C) 14 2/7%
    D) 13 1/2%
    E) None
    
    View Answer

    Option C
    Solution:
    2P=(P*14*r)/100
    200=14*r==> r=200/14 =14 2/7%.

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