SI & CI - 03 (RBI / IBPS / IPPB / SBI)

YOU CAN SOLVE THESE PROBLEMS BY DIGITAL ROOT METHOD


1. What will be the compound interest on a sum of Rs. 25,000 after 3 years at the rate of 12 p.c.p.a?
a) 10101        b) 10110   c) 21212     d) 10123.2    e) None of these

Let  P = 25000  n = 3yr          R = 12%

Now Amount (A) = P (1+R/100)^n

Now A = 25000 (1+12/100)^3

Now according to Digital Root Method

A = 2+5+0+0+0 (1+(1+2))^3

A = 7 (1+3)^3

A = 7 (4)^3

A = 7 (64) = 7(6+4) = 7(10) = 7(1+0) = 7

Now Amount Digital Root is = 7

And we know that Amount = P + CI         -------------- (1)

   Substitute the Digital Root of Amount and Principal in Eq -----(1)

Now     7 = 25000 + Ci

             7 = 7+ Ci

So, Clearly If Ci Digital Root is  9 then only LHS = RHS (According to Digital Root Method)

BY SAME METHOD YOU CAN SOLVE BELOW GIVEN QUESTIONS BY DIGITAL ROOT METHOD

2. A man saves Rs. 200 at the end of each year and lends the money at 5% compound interest. How much will it become at the end of 3 years?

a)  555      b) 662.02          c) 777.02         d) None of these

3. A bank offers 5% compound interest calculated on half-yearly basis. A customer deposits Rs. 1600 each on 1st January and 1st July of a year. At the end of the year, the amount he would have gained by way of interest is

A)  120     b) 121        c) 122   d) 123   e) None of these

4. The difference between simple interest and compound interest on Rs. 1200 for one year at 10% per annum reckoned half-yearly is:

a) 5         b) 3          c) 50       d) 6       e) None of thse

5. The simple interest on a certain sum of money for 3 years at 8% per annum is half the compound interest on Rs. 4000 for 2 years at 10% per annum. The sum placed on simple interest is:

A) 1750      b) 5750      c) 2750     d) 1000  e) None of these

6. The difference between compound interest and simple interest on an amount of Rs. 15,000 for 2 years is Rs. 96. What is the rate of interest per annum?

a) 7%      b) 6%     c) 7.5%     d) 8%    e) None of thse

7. The difference between the simple interest on a certain sum at the rate of 10% per annum for 2 years and compound interest which is compound every 6 months is Rs. 124.50. What is the principal sum?

a)      7500           b)  8000       c) 8500          d) 80000     e) None of these

8. A person lent out a certain sum on simple interest and the same sum on compound interest at a certain rate of interest per annum. He noticed that the ratio between the difference of compound interest and simple interest of 3 years and that of 20 years is 25 : 8. The rate of interest per annum is:

a) 12%         b) 13%      c) 12.5%      d) 15%    e) None

09. If a sum on compound interest becomes three times in 4 years, then with the same interest rate, the sum will become 27 times in:

a) 8 Yrs     b) 12 yrs          c) 24 Yrs      d) 25 Yrs     e) None of these

10.The compound interest on Rs. 30,000 at 7% per annum is Rs. 4347. The period (in years) is:

A)2.5     B) 2     C) 3     D)  4       E) none of these