NCERT Class XI Mathematics - Sequences and Series - Solutions
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Question : 108
Total: 106
A man deposited Rs 10000 in a bank at the rate of 5% simple interest annually. Find the amount in 15th year since he deposited the amount and also calculate the total amount after 20 years.
Solution:
Man deposited = Rs 10,000.
Rate of interest = 5%
Amount at the end of 1st year
= Rs.[ 10000 +
]
Since A = P +(
)
= Rs. [10000 + 500] = Rs. 10500
Amount at the end of 2nd year
= Rs.[ 10000 +
]
= Rs. [10000 + 1000] = Rs. 11000.
Similarly, amount at the end of 14th year
= Rs.[ 10000 +
]
= Rs. [10000 + 7000] = Rs. 17,000.
Hence, the amount at the end of 14th year = amount in the 15th year = Rs. 17000.
Now, amount at the end of 20th year = Rs.[ 10000 +
]
= Rs. [10000 + 10000] = Rs. 20000.
Rate of interest = 5%
Amount at the end of 1st year
= Rs.
Since A = P +
= Rs. [10000 + 500] = Rs. 10500
Amount at the end of 2nd year
= Rs.
= Rs. [10000 + 1000] = Rs. 11000.
Similarly, amount at the end of 14th year
= Rs.
= Rs. [10000 + 7000] = Rs. 17,000.
Hence, the amount at the end of 14th year = amount in the 15th year = Rs. 17000.
Now, amount at the end of 20th year = Rs.
= Rs. [10000 + 10000] = Rs. 20000.
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