The lifetimes of all the batteries produced by a certain company in a year have a distribution that is symmetric about the mean m. If the distribution has a standard deviation of d, what percent of the distribution is greater than m + d ?
(1) 68 percent of the distribution lies in the interval from m - d to m + d, inclusive.
(2) 16 percent of the distribution is less than m - d.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
没看懂题目,看懂了就很简单了
搞清楚对称指的什么意思
对称
搞清楚概念,还有注意对称
老师,难道这里默认是对称的吗?
題目有說是對稱的,distribution that is symmetric。
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