The scores on a placement test given to college
freshmen for the past five years are approximately
normally distribution with a mean = 74 and a variance
= 8. Would you still consider population variance = 8
to be a valid value if a random sample of 20 students
who take this placement test this year obtain sample
variance to be 20 ?
要如何得知是否為一個有效變異數數值呢??
小妹有搜尋到此題答案 http://ppt.cc/axNm
但卻不明白為何是取99%呢???
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