Given,
Rate = 15 % p.a
Time = 3 years
C.I – S.I = Rs.283.50
Let principal = P
So,
\(={P}[({1}+\frac{15}{100})^3-{1}]-\frac{P \times 15 \times 3}{100}\) = 283.50
\(={P}(\frac{23}{20})^3-{1}]-\frac{9p}{20}\) = 283.50
\(=\frac{4167p-3600p}{800}\) = 283.50
\(={567p}={283.50\times800}\)
\(={p}=\frac{283.50\times800}{567}\) = Rs. 4000
Hence,
Principal = Rs. 4000