SIMPLE INTEREST
- Interest is the money paid by the borrower to the lender for the use of money lent.
simple interest (SI) = (P*T*R) / 100
Here,
P = Principle
T = Time
R = Rate of Interest
similarly,
Principle (P) = (100*SI) / TR
Time (T) = (100*SI) / PR
Rate(R) = (100*SI) / PT
When
Principle = 100,
time = T
rate = R % per annum then,
SI = RT
Amount (A) = principal(P)+Simple Interest(SI)
A = P +SI
Problems :
1) Find the simple interest on Rs. 7,500 in 4 years at 15% per annum ?
solution : principle(P) simple interest(SI)
100 60
7500 ?
Here, say principle(P) = 100,
as we have seen above when P = 100 , simple interest(SI) = RT
in the question SI = 15(Rate)*4(time) = 60
principle (P) = 7500 (given in problem)
simple interest (SI) = ? (this simple interest is for principle 7500)
previously what we got simple interest (60) is for principle (100)
make cancellation only either in horizontal or in vertical directions
we get, 75*60 = 4500 (is the required answer)
now try to solve these
2) Find the simple interest on Rs. 8000 in three years and six months at 12% per annum ?
answer : RS. 3360
3) On what sum of money will be the simple interest be Rs. 2000 in 5 years at 8% per annum ?
answer : Rs. 5000
4) On what sum of money will the simple interest be Rs. 2400 in two years and six months at 12% per annum?
answer : 8000
Model - 2
5) In how many years will the sum of money become double at 4% per annum simple interest ?
solution : T = (SI * 100) / (P *R)
here say P = 100
given, A = 200
SI = A - P
SI = 200 - 100
SI = 100
now by using formula, T = (100*100) / (4*100)
T = 25 years
shortcut :
T = (100(times - 1)) / R
T = ((100(2 - 1)) / 4
T = 100 / 4
T = 25 years
now try to solve these
6) In how many years will the sum of money become twice at 10% per annum simple interest ?
answer : 10 years
7) At what rate % per annum simple interest will a sum of money become 9/5th of itself in 5 years?
answer : 16 trick : R = ((100(times - 1)) / T
Model - 3
8) The difference between the simple interest received from tow different sources on Rs. 1,500 for 3 years is Rs. 1,350. The difference between their rates of interest is ?
solution : Given, SI 1 - SI 2 = 13.5
R = (100 * SI) / (P * T)
here, R = r1 - r2
SI = (SI 1 - SI 2) difference in SI
r1 - r2 = (13.5 * 100) / (1500 * 3)
r1 - r2 = 13.5 / 45
r1- r2 = 135 / 450
r1 - r2 = 0.3 %
now try to solve these
5) In how many years will the sum of money become double at 4% per annum simple interest ?
solution : T = (SI * 100) / (P *R)
here say P = 100
given, A = 200
SI = A - P
SI = 200 - 100
SI = 100
now by using formula, T = (100*100) / (4*100)
T = 25 years
shortcut :
T = (100(times - 1)) / R
T = ((100(2 - 1)) / 4
T = 100 / 4
T = 25 years
now try to solve these
6) In how many years will the sum of money become twice at 10% per annum simple interest ?
answer : 10 years
7) At what rate % per annum simple interest will a sum of money become 9/5th of itself in 5 years?
answer : 16 trick : R = ((100(times - 1)) / T
Model - 3
8) The difference between the simple interest received from tow different sources on Rs. 1,500 for 3 years is Rs. 1,350. The difference between their rates of interest is ?
solution : Given, SI 1 - SI 2 = 13.5
R = (100 * SI) / (P * T)
here, R = r1 - r2
SI = (SI 1 - SI 2) difference in SI
r1 - r2 = (13.5 * 100) / (1500 * 3)
r1 - r2 = 13.5 / 45
r1- r2 = 135 / 450
r1 - r2 = 0.3 %
now try to solve these
9) The difference between the simple interest received from tow different sources on Rs. 500 for 2 years is Rs. 2.50. The difference between their rates of interest is ?
answer : 0.25 %
10) The simple interest on a certain sum at 5% per annum for 3 years and 4 years differ by Rs. 42. The sum is ?
solution:
5 % ------------------------- 3 years (SI = RT gives SI = 15)
same 5% for ------------------------- 4 years (SI = RT gives SI = 20)
---------------------------------
difference in SI = 5
--------------------------------
SI P
---- ----
(dif in SI) 5 100 ( as discussed above)
(Given) 42 ?
answer : Rs. 840
now try to solve these
11) The difference between the simple interest on a certain sum of money at 6% per annum for 10 years and 5% per annum for 2 years is Rs. 100. Find the sum ?
answer : Rs. 200
Model - 4
12) A sum of money doubles itself in 7 years. In how may years will it become four fold?
solution: doubles ---------- 7 years
thrice ---------- 14 "
four fold ---------- 21 " (required answer)
five ----------- 28 "
six ------------- 35 "
shortcut :
7(4 - 1) = 21 years (trick)
here, 7 years (given)
four fold = ? (21 years is required answer)
now try to solve these
13) A sum of money becomes double itself in 5 years and 6 months at simple interest. In how many years will it become five fold ?
answer : 22 years
14) A sum of money becomes thrice itself in 8 years at simple interest. In how many years will it become six times?
answer : 20 years
Read COMPOUND INTEREST from here
http://guidance2bankexams.blogspot.com/2013/01/compound-interest-in-case-of-compound.html
Read Other TOPICS from here
http://guidance2bankexams.blogspot.com/2013/01/profit-and-loss-this-chapter-is-largely.html
answer : 0.25 %
10) The simple interest on a certain sum at 5% per annum for 3 years and 4 years differ by Rs. 42. The sum is ?
solution:
5 % ------------------------- 3 years (SI = RT gives SI = 15)
same 5% for ------------------------- 4 years (SI = RT gives SI = 20)
---------------------------------
difference in SI = 5
--------------------------------
SI P
---- ----
(dif in SI) 5 100 ( as discussed above)
(Given) 42 ?
answer : Rs. 840
now try to solve these
11) The difference between the simple interest on a certain sum of money at 6% per annum for 10 years and 5% per annum for 2 years is Rs. 100. Find the sum ?
answer : Rs. 200
Model - 4
12) A sum of money doubles itself in 7 years. In how may years will it become four fold?
solution: doubles ---------- 7 years
thrice ---------- 14 "
four fold ---------- 21 " (required answer)
five ----------- 28 "
six ------------- 35 "
shortcut :
7(4 - 1) = 21 years (trick)
here, 7 years (given)
four fold = ? (21 years is required answer)
now try to solve these
13) A sum of money becomes double itself in 5 years and 6 months at simple interest. In how many years will it become five fold ?
answer : 22 years
14) A sum of money becomes thrice itself in 8 years at simple interest. In how many years will it become six times?
answer : 20 years
Read COMPOUND INTEREST from here
http://guidance2bankexams.blogspot.com/2013/01/compound-interest-in-case-of-compound.html
Read Other TOPICS from here
http://guidance2bankexams.blogspot.com/2013/01/profit-and-loss-this-chapter-is-largely.html
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