A Sum of money lent out at C.I. at a certain rate per annum becomes two times of itself in 6 years.Find in how many years will the money become eight times of itself at the same rate of interest per annum.
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Answered by
3
Answer:
Correct option is
A
15
Let Principal = Rs. x = Amount in 5 years = Rs .2x
A=P(1+
100
r
)
n
⇒2x=x(1+
100
r
)
5
⇒2=(1+
100
r
)
5
For the second part : P= Rs x and A = Rs. 8x
∴A=P(1+
100
r
)
n
⇒8x=x(1+
100
r
)
n
⇒8=(1+
100
r
)
n
i.e. (2)
3
=(1+
100
r
)
n
⇒[(1+
100
r
)
5
]
3
=(1+
100
r
)
n
[∵2=(1+
100
r
)
5
]
⇒(1+
100
r
)
15
=(1+
100
r
)
n
⇒n=15
i.e. Time Required = 15 years
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