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博士級忠實車迷
Lv 7
博士級忠實車迷 發問於 教育及參考書小學及中學教育 · 8 年前

proportion and probability

1. A software house found that the project value received over the past year were approximately normally distributed , with a mean of $43,000 and a standard deviation of $8,500 . Suppose the project value remains the same next year.

a) What proportion of new projects would you expect to be $35,000 or less?

b) What proportion of new projects would you expect to be between $30,000 and $45,000?

2.The probability that a bearing meets a specification is 0.92 . Six bearings are picked at random . Calculate the probability that

a)all six meet the specification

b)more than four meet the specification

c)one or none meets specification and

d)and exactly four meet the specification

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