easy probability question

[Victor]

you have 4 dice. you roll them all. what are the chances that exactly 1 die shows a 3 or a 4 (and no other 3s or 4s are showing)?

[MagicFlea]

(1/3) * (2/3)^3 * 4 = 32/81

first, consider the first die coming up 3 or 4 and the rest coming up not... then multiply by four to account for other possibilities.

[Victor]

thanks a lot.