Do you calculate the interest for the day you make payment to a loan? (S=P(1+i)^n)

My question's below, I'm wondering n=1 or n=2?

The bank borrowed $10 500 for one day at a rate of j_365= 3.75%, but the next day they needed to borrow another $3750, but the rate increased to

j_365= 4%.What does Bank owe if they repay all of their debts the day after they borrowed $3750 and the rate j_365 did not change?