add maths

~Dr3aM~

A box contains 10 cards with numbers 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19 written on each card respectively. Two cards are drawn randomly from the box. Find the probability that the sum of the digits for both cards drawn is greater than 8.

请问下这题题目有问题吗?

ralywong

没有问题啊！同时拿两张卡的话你就当作两张卡是分开拿，然后是没有放回去的。所以
probability = 2/10 x 1/9 = 1/45

~Dr3aM~

ralywong 发表于 16-11-2012 03:21 PM
没有问题啊！同时拿两张卡的话你就当作两张卡是分开拿，然后是没有放回去的。所以
probability = 2/10 x 1 ...

Find the probability that the sum of the digits for both cards drawn is greater than 8.
这句弄到我有点乱...我还以为他的probability是1 =.=

DKofCWK

~Dr3aM~ 发表于 16-11-2012 04:55 PM
Find the probability that the sum of the digits for both cards drawn is greater than 8. [/backcolo ...

题目有点怪怪的。。。
应该写sum of digits for each card drawn is greater than 8，
刚刚我还以为他要我们找两张卡的digits加起来大过八的probability

~Dr3aM~

DKofCWK 发表于 16-11-2012 10:01 PM
题目有点怪怪的。。。
应该写sum of digits for each card drawn is greater than 8，
刚刚我还以为他要 ...

我也是以为 -_- 所以我以为有问题...

~Dr3aM~

谁是perak人? 我昨天做了perak的trial add maths考卷... 好像它给的skema jawapan有错哦~ paper 1的...