₹ 45000 is deposited at compound interest for 4 years. The rates are 6% (1st year), then increase by 1% each year (so 7%, 8%, 9%). Find the approximate amount at the end of 4 years.
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For varying yearly rates, multiply sequential growth factors $(1+r_i)$; rounding the final factor gives a quick estimate.
The final amount is calculated as $P(1+0.06)(1+0.07)(1+0.08)(1+0.09)$. Therefore, $A=45000\times1.06\times1.07\times1.08\times1.09 \approx 45000\times1.335 \approx ₹ 6.01\times10^4$. \(\Rightarrow\) Approximately ₹ 60000.