Principal=Rs.20,000
Time =1 year compounded semi-annually
Rate=16%
As the interest is compounded semi-annually so the rate is divided by 2 and the time is multiply by 2
∴A=P(1+R2×100)T×2
⇒A=20,000(1+8100)2
⇒A=20,000×108100×108100
⇒A=2×108×108
⇒A=Rs.23328
∴C.I=23328−20000=Rs.3328