Answer:
Interest= $ 18.73
Step-by-step explanation:
Given : $600 at 9.5% for 120 days
To find : Find the interest due
Solution :
Simple interest formula 
Principle(P)=$600 , rate(r)=9.5%=0.095 , time (t)= 120 days
In years, 1 year = 365 days
1 day =
year
120 days =
year
Put values in the formula


Therefore, Interest= $ 18.73

Let
, so that
:

Now the ODE is separable, and we have

Integrating both sides gives

For the integral on the left, rewrite the integrand as

Then

and so


Given that
, we find

so that the particular solution to this IVP is

Wouldn't it be -1 (minus one)? 12 - 1 = 11 and 9 - 1 = 8.