$X$ borrowed Rs.$150000$ from $Y$ at the rate of $21$ percent per year. At the end of $15$ months, how much compound interest should $X$ pay compounded half yearly?
My Attempt.
I solved it using the formula ; $$C.I=P[(1+\frac {R}{200})^{2T} (1+\frac {MR}{1200})-1]$$. Where, T=1 year and M=3months.
I got the answer as $C.I=Rs. 42759.3219$ but the answer given in my book is $Rs. 49500$?
How did this happen? Please help me to get the correct answer.