To find the approximate annual interest rate to the nearest tenth of a percent, we can use the formula:
I = Prt
where I is the interest charged, P is the principal amount borrowed, r is the annual interest rate as a decimal, and t is the time in years.
We know that Darcy borrowed $3600 for 7 months, which is equivalent to 7/12 years. We also know that the interest charged was $250.
Substituting these values into the formula, we get:
250 = 3600r(7/12)
Simplifying this equation, we get:
r = 250 / (3600 * 7/12)
r ≈ 0.0903 or 9.03%
Therefore, the approximate annual interest rate to the nearest tenth of a percent is 9.0%.