Try your hand at

[Guest]

Test No. incompl/inter-1 "Applying for that Job", question 9

Have you ever tried your ......... at running a business?

(a) arm
(b) finger
(c) hand
(d) leg

Test No. incompl/inter-1 "Applying for that Job", answer 9

Have you ever tried your hand at running a business?

Correct answer: (c) hand
_________________________

Why we can't use "arm", "finger", and "let" in place of "hand"?

[Torsten]

Because it's a fixed expression. Please, take a look at this:
http://www.english-test.net/forum/ftopic1812.html

TOEFL listening lectures: A university lecture by a professor of American History