c****l
发帖数: 1280 | 1 I remembered that someone post a brain teaster question, but cannot find it
now. Based on my memoery, here is it:
a dice with all black surfaces and white inside. cut the dice into 27 small
cubes with 6 cuts. and take one to roll, what is the probabability that a
black surface is on the top?
=> is the question correct?
=> 6/(12+6 ) = 1/3 is the correct answer? |
h**6
发帖数: 4160 | 2 (8/27)*(3/6) + (12/27)*(2/6) + (6/27)*(1/6) + (1/27)*(0/6) = 1/3 |
p****x
发帖数: 707 | 3 6*9=54 small black faces. total faces 27*6
54/(27*6) = 1/3
【在 h**6 的大作中提到】
: (8/27)*(3/6) + (12/27)*(2/6) + (6/27)*(1/6) + (1/27)*(0/6) = 1/3
|
c*******a
发帖数: 45 | 4 正解
【在 p****x 的大作中提到】
: 6*9=54 small black faces. total faces 27*6
: 54/(27*6) = 1/3
|
h*******n
发帖数: 614 | 5 问题对，答案也对。这题还可以进一步改成cut n刀，问得到黑面的概率。答案是1/（n
+1) |
t*****j
发帖数: 1105 | 6 （9×6）/（27×6） = 1/3 每个小块的每个面都是等概率出现的。
it
small
a
【在 c****l 的大作中提到】
: I remembered that someone post a brain teaster question, but cannot find it
: now. Based on my memoery, here is it:
: a dice with all black surfaces and white inside. cut the dice into 27 small
: cubes with 6 cuts. and take one to roll, what is the probabability that a
: black surface is on the top?
: => is the question correct?
: => 6/(12+6 ) = 1/3 is the correct answer?
|
