大师作文网Gmat 数学DS题目
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Gmat 数学DS题目
During an experiment, some water was removed from each of 6 water tanks. If the standard deviation of the volumes of
water in the tanks at the beginning of the experiment was 10 gallons, what was the standard deviation of the volumes of
water in the tanks at the end of the experiment?
(1) For each tank, 30 percent of the volume of water that was in the tank at the beginning of the experiment was removed
during the experiment.
(2) The average (arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons.
求翻译和详解
During an experiment, some water was removed from each of 6 water tanks. If the standard deviation of the volumes of
water in the tanks at the beginning of the experiment was 10 gallons, what was the standard deviation of the volumes of
water in the tanks at the end of the experiment?
(1) For each tank, 30 percent of the volume of water that was in the tank at the beginning of the experiment was removed
during the experiment.
(2) The average (arithmetic mean) volume of water in the tanks at the end of the experiment was 63 gallons.
求翻译和详解
方差s^2=[(x1-x)^2+(x2-x)^2+......(xn-x)^2]/n 即将组内每个数减去平均值的平方,然后除以(n-1),n为组内样本个数标准差=方差的算术平方根标准差是反应一组数据离散程度最常用的一种量化形式，是表示精密确的最要指标...