Find the nominal interest rate?

[hank]

I take out a loan for $1200. After one week, the bank expects me to repay $1240.

What is the nominal interest rate?

I figured it would be 40/1200 * 52, but that is greater than 100%.

Help?

 

[Denis]

Not "precise" but close; 52 * 40 = 2080 = equivalent interest for 1 year, so:
1200(1 + r) = 3280
r = 1.733333 ; so 173 1/3 %

The "actual" true annual rate will be slightly higher, since the $40 is paid after 1 week, not a year later...