The maturity value of a R.D
account is Rs.16176. If the
monthly installment is
Rs.400 and the rate of
interest is 8%, then the time
of this account is:
Answers
Answer:
Monthly instalment, P=Rs. 400
number of months=n
Rate of interest, r=8%
Simple interest, ∫I=P×
2×12
n(n+1)
×
100
r
=400×
100
8
×
24
n(n+1)
=
3
4
n(n+1)
Given, maturity value of RD account =Rs. 16,176
⇒400×n+
3
4
n(n+1)=16,176
⇒400n+
3
4
n
2
+
3
4
n=16176
⇒
3
4
n
2
+
3
4
n+400n−16176=0
⇒4n
2
+4n+1200n−48528=0
⇒4n
2
+1204n−48528=0
⇒4(n
2
+301n−12132)=0
⇒n
2
+301n−12132=0
⇒n
2
+337n−36n−12132=0
⇒n(n+337)−36(n+337)=0
⇒(n−36)(n+337)=0
⇒n=36 or n=−337, which is neglected since number of months cannot be negative.
Hence time period of RD account =36 months =3 years.
Answer:
Monthly instalment, P=Rs. 400
number of months=n
Rate of interest, r=8%
Simple interest, ∫I=P×2×12n(n+1)×100r
=400×1008×24n(n+1)
=34n(n+1)
Given, maturity value of RD account =Rs. 16,176
⇒400×n+34n(n+1)=16,176
⇒400n+34n2+34n=16176
⇒34n2+34n+400n−16176=0
⇒4n2+4n+1200n−48528=0
⇒4n2+1204n−48528=0
⇒4(n