Interest accrued to Rupa across banks

In Bank A, effective interest rate for 1 year compounded half yearly at 6% p.a. (3% per half-year): $\text{Effective rate} = (1.03)^2 - 1 = 0.0609 = 6.09\%$

Raju's interest in Bank B for period $t$ at simple interest rate $r$ equals Bank A's 1-year interest: $I_{Raju} = P_R \cdot r \cdot t = P_R \times 0.0609 \implies rt = 0.0609$

Rupa invests ₹ 10,000 in Bank C at rate $2r$ for period $2t$: $I_{Rupa} = 10000 \times (2r) \times (2t) = 40000 \times (rt)$ $I_{Rupa} = 40000 \times 0.0609 = 2436$.