The general principle of borrowing at an interest rate is "lower the interest rate, lesser the interest paid". This is because a lower interest rate is essentially lowering the cost of your loan. For example if the loan you have taken is Rs 100, with an interest rate of 13% you are paying back Rs 113 to the lender. Whereas, with an interest rate of 9%, you are paying back Rs 109. Hence, lower the interest rate, lower the costs you face. Furthermore, since the return on investment of the company is 10%-12%, borrowing at an interest rate of 13 % will definitely give negative returns.