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jeanielim

2012-11-9 11:24 PM

问题：A class consists of 8 males and x female students.If the probability of 2 randomly chosen male students is 28/33 ,calculate the value of x.

请问这题怎么做？？求高人解答..谢谢！答案是：4

Soo_135

2012-11-10 12:19 AM

问题有错吗？

jeanielim

2012-11-10 12:21 AM

我也在想这个问题。。应该是书本的问题了。。。

Soo_135

2012-11-10 12:22 AM

如果答案是4，问题里the probability of 2 randomly chosen male students is 28/33 就错了，是14/33 才对

jeanielim

2012-11-10 12:24 AM

还有一题：In a geometric progression, the sum of the first 5 terms is 248 and the sum of the next 5 terms is 7/3/4.Find the common ratio and the first term. ans:r=1/2 a=128

jeanielim

2012-11-10 12:27 AM

回复 4# Soo_135

嗯嗯。。刚刚问了人。。他也说应该是14/33.。。
真是的。。我不知在这题上花了多少时间。。==