correct answer is: b) ₹ 3500

Explanation

Here,
Amounts = ₹ 3605
Time = 219 days or \frac{219}{365} years
Rate = 5 %
We know, Amounts =\left(Principal+S.I\right)
\therefore₹3605=\left(P+S.I.\right) _{[put A’s value]}
\rightarrow₹3605=P+\left(\frac{p\times r\times t}{100}\right) ^{_{[put S.I. formula]}}
\rightarrow₹3605=P+\left(\frac{p\times5\times219}{100\times365}\right)
\rightarrow₹3605=\left(p+\frac{1095p}{36500}\right)
\rightarrow₹3605=\left(\frac{36500p+1095p}{36500}\right)
\rightarrow₹3605=\frac{37595p}{36500}
\rightarrow37595p=₹\left(36500\times3605\right)
\rightarrow p=₹\left(\frac{36500\times3605}{37595}\right)
\rightarrow p = ₹3500
\therefore The sum is ₹3500 .
Ans: The sum ₹3500 .

Another way to ask this same question is:
1. Calculate the principal sum with an interest rate of 5% per annum, given that the amount is ₹3605 in 219 days.
2. Principal sum formula for interest calculation at 5% per annum in 219 days.
3. How to find the principal amount when the interest rate is 5% and the time period is 219 days?
4. Solve for principal sum with interest rate 5% and time period 219 days.
5. How does the principal amount vary at 5% interest over 219 days compared to other scenarios?