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匿名 發問於 科學及數學數學 · 7 年前

求教!新一題英文Statistical~~~

Question 2

(b) The Hong Kong Red Cross Blood Transfusion Service wishes to select a stratified sample of 5000 blood donors from districts 10, 11, 12 and 13. The table below shows the number of blood donors in each district.

District code no:

10 11 12 13

Number of blood donors:

32000 30000 18000 15000

Explain how such a stratified random sample of 5000 blood donors can be taken.

(13 marks)

ps.10配32000,11配30000.....

請列式

1 個解答

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  • 7 年前
    最愛解答

    Total number of blood donors = 32000 + 30000 + 18000 + 15000 = 95000.

    Assign the 5000 samples according to the ratio of the number of blood donors in each district to the total number of blood donors.

    That is, to sample in district 10: 5000 * 32000/95000 = 1684 blood donors;

    to sample in district 11: 5000 * 30000/95000 = 1579 blood donors;

    to sample in district 12: 5000 * 18000/95000 = 947 blood donors;

    to sample in district 13: 5000 * 15000/95000 = 789 or 790 blood donors.

    This is stratified sampling. In this way, the proportion of blood donors in each sample can be maintained.

    Explanation:

    http://en.wikipedia.org/wiki/Stratified_sampling

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