4.
The difference between compound interest
and simple interest of the same rate for
Rs 5,000 for 2 years is Rs. 72. Find the
rate of interest.
Answers
Answered by
0
Answer:
Let the rate per cent p.a.be r. Then,
S.I.=Rs.(5000×
100
r
×2)=Rs.100r
C.I.=Rs.
⎣
⎢
⎡
5000(1+
100
r
)
2
−5000
⎦
⎥
⎤
=Rs.5000
⎣
⎢
⎡
(1+
100
r
)
2
−1
⎦
⎥
⎤
=Rs.5000[(1+
10000
r
2
+
100
2r
)−1]
=Rs.5000(
10000
r
2
+
50
r
)=Rs.
10000
5000(r
2
+200r)
=Rs.(
2
r
2
+100r)
∴C.I.−S.I.=72
⇒
2
r
2
+100r−100r=72
⇒
2
r
2
=72
⇒r
2
=144
⇒r=12%p.a.
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