作者a2515125 (Bobshih)
看板GMAT
标题[计量] pp1 请教
时间Mon Sep 14 00:00:11 2009
A vending machine is designed to dispense 8 ounces of coffee into a cup.
After a test that recorded the number of ounces of coffee in each of 1,000
cups dispensed by the vending machine, the 12 listed amounts, in ounces,
were selected from the data. If the 1,000 recorded amounts have a mean
of 8.1 ounces and a standard deviation of 0.3 ounce, how many of the 12
listed amounts are within 1.5 standard deviations of the mean?
(A) Four
(B) Six
(C) Nine
(D) Ten
(E) Eleven
请问这题如何解?
SD=0.3
Mean=8.1
范围7.8~8.4
然後呢~"~
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