Quantitative Aptitude: Simple Interest/Compound Interest Set 1

Simple Interest/Compound Interest (SI/CI) Questions with tricks for SBI PO, IBPS PO, NIACL, NICl, Dena Bank PO PGDBF, BOI, Bank of Baroda and other competitive exams 

  1. If the difference between Simple Interest and Compound Interest at 10% p.a rate of interest for 3 years is Rs. 930, then find the Sum.
    A) Rs 25,000
    B) Rs 30,000
    C) Rs 35,000
    D) Rs 40,000
    E) None of these
    View Answer
    Option B
    Solution
    :
    On SI, Rate for 3 years=3*10=30%
    On CI rate for 3 years – 10%=1/10
    10—–11
    10—–11
    10—–11
    1000—-1331
    =1331-1000/1000 *100=33.1%
    Difference=33.1-30=3.1%
    3.1%=930
    100%=Rs 30,000
  2. On a certain rate of interest a sum of Rs 5000 becomes Rs 16,200 in certain years at compound interest. In half of the time given, this sum will become?
    A) Rs 10,000
    B) Rs 5,600
    C) Rs 9,000
    D) Cannot be determined
    E) None of these
    View Answer
    Option C
    Solution
    :
    a————————b—————c
    5000—————– X  ————16200
    ———–t——————- t ————
    As we have to calculate the sum for half time, both time period is same, and hence
    a:b = b:c
    5000:x = x:16200
    x=Rs 9000
  3. If a certain sum becomes double in 3 years at certain rate of interest at C.I. Then in how many years it will become 16 times?
    A)12 years
    B) 24 years
    C) 8 years
    D) Cannot be determined
    E) None of the above
    View Answer
    Option A
    Solution
    :
    In C.I P increases like
    P——-2P——–4P———8P——–16P
    —-3yrs—–3yrs—–3yrs——-3yrs
    total=3+3+3+3=12 years
  4. Ram invests two sum of money A and B at 10% p.a. and 20% p.a respectively at CI for 2 years. IF the total interest on both the sum is Rs 5350 then find the sum invested in A if the total sum of A and B was Rs 20,000?
    A) Rs 5,000
    B) Rs 10,000
    C) Rs 12,000
    D) Rs 15,000
    E) None of these
    View Answer
    Option D
    Solution
    :
    At 10% CI in 2 years=21 %
    At 20% Ci in 2 years =44%
    and 5350 is 107/4% of 20000, by using allegation
    A                                              B
    21                                             44
    107/4
    3                                               1
    A=3/4*20000= Rs 15000
  5. The compound interest on a certain sum for 2 years at a certain rate of interest is Rs 1025 and Simple Interest on the same sum, same time and same rate of interest is Rs 1,000. Then find the C.I for same sum in 3 years.
    A) Rs 1575.25
    B) Rs 1576.25
    C) Rs 1576.75
    D) Rs 1575.75
    E) None of these
    View Answer
    Option B
    Solution
    :
    SI for 2 years = Rs 1000 =.> Si 1 year = Rs 500
    In the second years Rs 25 is added in CI (1025-1000) which is 5% of 500
    Hence R=5%
    5%=500
    100%=10000
    sum=10000
    CI for 3 years= RS 1576.25
  6. A sum becomes triple in 6 years at S.I. The same sum will become 19 times in how many years?
    A) 50 years
    B) 48 years
    C) 54 years
    D) 57 years
    E) None of these
    View Answer
    Option C
    Solution
    :
    SI=A-P=> A=3P as sum triples
    SI=3P-P=2P in 6 years
    In 19 times SI=18 P—54 years (2:6 hence 18=54)
  7. A sum of Rs 343 becomes 512 in 3 years at C.I. Find the rate of interest.
    A) 14 (2/7) %
    B) 12.5 %
    C) 8 (2/3) %
    D) 16 (2/3) %
    E) None of these
    View Answer
    Option A
    Solution
    :
    Sum=353; Amount=512
    as many year, put that many root i.e
    cuberoot(343): cuberoot(512)
    7:8
    rate=(8-7)/7 *100 =14 (2/7)%
  8. Find the C.I on Rs 20,000 at 10% rate of interest in 2 years if compounded half yearly. (Approximately)
    A) Rs 4210
    B) Rs 4310
    C) Rs 4410
    D) Rs 4510
    E) None of these
    View Answer
    Option B
    Solution
    :
    In half yearly=> Time-double; Rate= half
    Rate=5% ; Time=4 years; Sum = Rs 20,000
    1 years————–2 years————3 years———-4 years
    1000—————–1000—————1000————-1000
    ————————50——————50—————–50
    ———————————————50—————–50
    ———————————————2.5—————-50
    —————————————————————–2.5
    —————————————————————–2.5
    —————————————————————–2.5
    —————————————————————-0.125
    Total = Rs 4000 +300 + 10+0.125= Rs 4310.125
  9. A sum of Rs 6,000 was taken as a loan. This is to be repaid in two equal annual installments. If the rate of interest is 20% compounded annually then find the value of each installment.
    A) Rs 4400
    B) Rs 2220
    C) Rs 4320
    D) Rs 4420
    E) None of these
    View Answer
    Option C
    Solution
    :
    Formula= x/(1+R/100)^T
    x/ (1+20/100)^1 + x/(1+20/100)^2 = 6600
    solve and get x=4320
  10. If the ratio of difference between CI and SI for 3 years and 2 years is 31:10, then find the Rate of Interest.
    A) 11.11%
    B) 10%
    C) 20%
    D) 25%
    E) None of these
    View Answer
    Option B
    Solution
    :
    Sum= A
    Interest= B
    A——–A———A
    ———-B———B
    ———————B
    ———————C
    CI for 3 years=3A+3B+C
    SI for 3 years =3A
    Diff= 3B+cCI for 2 years=2A+B
    SI for 2 years=2A
    diff=B
    ratio=(3B+C)/B=31/10
    B=10; C=1
    Rate=C/B=1/10=10%

 

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