匿名
匿名 發問於 科學及數學數學 · 6 年 前

急做statistical probability..20

(a) Hong Kong Government is promoting the use of energy efficient home appliances, including light bulbs. According to results of a concern group, the life-time of a particular brand of energy saving light bulb is found to be normally-distributed with mean life time of 5864 hours and standard deviation of 328 hours.

(i) Find the value of t hours such that 95% of such light bulbs can last longer than t hours. (5 marks)

(b) The production of energy saving light bulbs requires quality control process. Each light bulb is inspected before being shipped to the market. On average, 10% of such light bulbs produced are defective and 10% of such light bulbs are misclassified in the quality control process.

(i) Present the above information with a tree diagram. (3 marks)

1 個解答

評分
  • 6 年 前
    最佳解答

    Please read:

    圖片參考:http://imgcld.yimg.com/8/n/HA00430218/o/2013120601...

    2013-12-11 19:25:06 補充:

    表的左方加上表的上方的數是quantile

    -(1.60 + 0.04) = -1.64

    睇 -1.64 對應表中的 .0505 代表 standard normal -1.64 以左的 area/proportion/probability 是 5.05%

    睇 -1.65 對應表中的 .0495 代表 standard normal -1.65 以左的 area/proportion/probability 是 4.95%

    2013-12-11 19:25:17 補充:

    如果問那個quantile可使standard normal 以左的 area/proportion/probability 是 5% (即以右的是 95% ), 那從上述資料可以推出是 -1.645

    你看:

          以左     以右

    -1.64   5.05%  94.95%

    -1.65   4.95%  95.05%

    所以

    -1.645  5%   95%

還有問題嗎?立即提問即可得到解答。