Find the compound interest on a sum of Rs.40,000 at 20% p.a. for 2 years 3 months when the interest is compounded 9 monthly.

20,835

Interest rate when compounded 9 monthly = \(\frac{9}{12}\) ×20% = 15% 

 2 year 3 months = 27 months (creates 3 cycle)

Compound interest for 3 cycle of 9 months at the rate of 15% = \(\frac{3}{20}\)

Principal  :  Amount

    20       :     23

    20       :     23

    20       :     23  

  8000     :   12167

⇒ C.I = Amount  - Principal = 4167

⇒ 8000R = 40000

⇒ 1R = 5

⇒ C.I. = 4167 × 5 = 20,835