Solving Pendulum Question on Physics Quiz: Length 2m, 10 Oscillations in 32 secs

[NoHeart]

I'm having a problem with just one question on this week's physics quiz-
a pendulum with length 2m on a moon oscillates 10 times in 32 seconds, what is the gravity on this moon?

i know (or thought i knew) how to get the answer to this, with the simple formula g=4pi^2L/T^2

10 oscillations in 32 seconds means a frequency of .32Hz, right? and T=1/f so T=3.125, right?
so when i plug in T as 3.125 and L as 2, i get an answer of 8.08 m/s^2

this is not one of the answer choices, however. my choices are 2.54, 9.86, 7.71, and 3.86
what have i done wrong?

 

[Pyrrhus]

Your approach is correct, Your arithmetic is wrong. The Period would be equal to 3.2

 

[bahamut]

10 oscillations in 32 seconds means a frequency of .32Hz, right? and T=1/f so T=3.125, right?

Actually,you are not right.
T=t/r=32/10=3.2 second.