Wednesday, January 15, 2014

SIMPLE INTEREST : Study Material QA series-11




Welcome to Coaching Genie's series-11 of Quantitative Aptitude. The Best free IBPS PO Clerk coaching , study materials and practice tests.

This is a series on SIMPLE INTEREST

When a person(borrower) borrows (lends) money from other person (money lender) or from a bank for a certain time and after that specified time he returns the money back to money lender or bank with extra amount, then that extra amount is called interest.
If a certain amount and at a certain rate interest are same for all the given years then it is called Simple Interest. It is changed on principal only.

Important Formulas for Simple Interest are as follows:

\[\blacksquare S.I = A - P\]
\[\blacksquare S.I=\frac{P\times R\times T}{100}\]
\[\blacksquare P =\frac{ S.I\times 100}{T\times R}\]
\[\blacksquare R =\frac{ S.I\times 100}{P\times T}\]
\[\blacksquare T =\frac{ S.I\times 100}{P\times R}\]

Where A ➙ Amount
            P ➙ Principal
            T ➙ Time
            R ➙ Rate
           S.I ➙ Simple Interest

Principal - Initial amount or the amount borrowed is called the principal.
Amount - Sum of principal and extra amount which a borrower has to return is called amount.

◉ Relation of Amount and Principal
Amount ✖ 100 = Principal(100 + RT)

✪ Type-1

101. Find Amount on ₹8500 at 7% p.a for 6 years?
a)₹14120
b)₹13250
c)₹12070
d)₹11160
e)₹10880

 

102. At what rate % of S.I ₹3600 will become ₹5976 in 6 years?
a)10%
b)11%
c)12%
d)13%
e)14%

 

✪ Type-2:

\[\blacksquare Difference-of-S.I =\frac{P\times T\times Difference-of-Rate}{100}\]

103. The difference of simple interest on ₹6000 from two banks in 3 years is ₹540. Find difference of their rate?
a)7%
b)6%
c)5%
d)4%
e)3%

 

✪ Type-3:

Trick : If S.I on a sum of money is x/y of the principal, and the number of years is equal to the rate percent per annum. Then

\[\blacksquare Time=Rate=\sqrt{\frac{x}{y}\times 100}\]

104.The S.I on a sum of money is 16/25 of the principal, and the number of years is equal to the percent per annum.Find rate ?
a)5%
b)6%
c)7%
d)8%
e)9%



✪ Type-4:

Trick : If a certain sum of amount becomes x times in t years then Rate in % is
\[\blacksquare Rate=[\frac{(x-1)\times100}{t}]\%\]
Trick : If a certain sum of money becomes x times at the rate of r% then
\[\blacksquare Time=[\frac{(x-1)\times100}{r}]\space years\]

105.A sum of money becomes 4 times in 12 years at a certain rate of S.I. Find rate percent per annum?
a)15%
b)18%
c)22%
d)25%
e)27%



106.In how many years a certain sum of money becomes 3 times at the rate of 20% per annum at S.I?
a)4
b)6
c)8
d)10
e)12



Type-5

Trick : If a certain sum becomes x times at the rate of r1% and becomes y times at the rate of r2% then,
\[\blacksquare \space r_{2}=[\frac{(y-1)}{(x-1)}]\times r_{1}\space\%\]
Trick : If a sum becomes x times in t1 years and y times in t2 years at a S.I then,
\[\blacksquare \space t_{2}=[\frac{(y-1)}{(x-1)}]\times t_{1}\space years\]

107.A sum becomes 4 times in 10 years. In how many years will it amount to 10 times at the same rate of S.I?
a)18 years
b)22 years
c)26 years
d)28 years
e)30 years



Type-6

If rate of interest are r1%, r2%, r3%, r4% for t1, t2, t3, t4 years respectively then
\[\blacksquare S.I=P[\frac{t_{1}r_{1}+t_{2}r_{2}+t_{3}r_{3}+t_{4}r_{4}+....}{100}]\]
\[\blacksquare Principal=[\frac{S.I\times100}{t_{1}r_{1}+t_{2}r_{2}+t_{3}r_{3}+t_{4}r_{4}+....}]\]
\[\blacksquare Amount=P[1+\frac{t_{1}r_{1}+t_{2}r_{2}+t_{3}r_{3}+t_{4}r_{4}+....}{100}]\]

108.Find the S.I for a principal of ₹5000 at a rate for interest 7% for the first 2 years then 8% for the next 3 years then 9% for the next 4 years and 10% for the next 5 years?
a)5600
b)5800
c)6000
d)6200
e)6400



✪ Type-7

Trick : If at a S.I a sum becomes A1 at the rate of r1% and becomes A2 at the rate of r2% then
\[\blacksquare P=[\frac{A_{2}r_{1}-A_{1}r_{2}}{r_{1}-r_{2}}]\]
\[\blacksquare Time=[\frac{A_{2}-A_{1}}{A_{2}r_{1}-A_{1}r_{2}}]\times100\]

109.If at a S.I a sum becomes ₹6500 at the rate of 8% and becomes ₹5000 at the rate of 5% then what is the principle invested?
a)2500
b)3500
c)4500
d)5500
e)6500



✪ Type-8

Trick : If a sum becomes A1 in t1 years and A2 in t2 years at S.I then
\[\blacksquare P=\{A_{1}-\frac{t_{1}}{(t_{2}-t_{1})}\times(A_{2}-A_{1})\}\]

110.Find the sum which amount to ₹1250 in 4 years and becomes ₹2000 in 8 years at rate of simple interest.
a)250
b)500
c)750
d)1000
e)1250



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