A first order reaction has a rate constant of 0.0733 s−1.

What is the half life for this reaction in seconds?

when I plug in the numbers in the formula, my answer was 9.45. But on the computer it says the answer is wrong. How do I find the right answer?

If I use (ln 2/0.0733) I obtain 9.4563 which I would round to 3 s.f. as 9.46. Perhaps that is the trouble; i.e., 0.693/0.0733 returns 9.45 but ln 2/0.0733 returns 9.456.