標題:
Statistics問題
發問:
The share prices of a bank at the end of trading each day for the last year follow the normal distribution. Assume there are 240 trading days in the year. The standard deviation was $2.25 per share and the mean price was $42.00 per share.i) What proportion of of the days was the price over $45? How many days... 顯示更多 The share prices of a bank at the end of trading each day for the last year follow the normal distribution. Assume there are 240 trading days in the year. The standard deviation was $2.25 per share and the mean price was $42.00 per share. i) What proportion of of the days was the price over $45? How many days would you estimate in which the share price was over $45? ii) What was the approximate share price on the 6th highest day of the year? 更新: 要步驟,謝謝
最佳解答:
Let X~N(42, 2.25^2) (i) P(X>45) =P(Z> (45-42)/2.25) =P(Z>1.3333) = 1 - 0.9082 【Check your normal table!】 = 0.0918 240*0.0918 = 22.03 So 9.18% of the days would the price be over $45. There would be 22 days which the price be over $45. (ii) 6th highest day => 6/240 = 0.0250 of the days will be higher Let t be the required price, then P(X>t) = 0.0250 P(Z> (t-42)/2.25) = 1 - 0.9750 (t-42)/2.25 = 1.96 【Check your normal table!】 t = 42 + 1.96*2.25 = 46.41 The required price is $46.41 2012-12-04 09:08:06 補充： 240天內，會有2.5%的日子，股價比「第六高股價的日子」更高
6th highest day => 6/240 = 0.0250 of the days will be higher 這問這是什麼意思??謝謝
Statistics問題
發問:
The share prices of a bank at the end of trading each day for the last year follow the normal distribution. Assume there are 240 trading days in the year. The standard deviation was $2.25 per share and the mean price was $42.00 per share.i) What proportion of of the days was the price over $45? How many days... 顯示更多 The share prices of a bank at the end of trading each day for the last year follow the normal distribution. Assume there are 240 trading days in the year. The standard deviation was $2.25 per share and the mean price was $42.00 per share. i) What proportion of of the days was the price over $45? How many days would you estimate in which the share price was over $45? ii) What was the approximate share price on the 6th highest day of the year? 更新: 要步驟,謝謝
最佳解答:
Let X~N(42, 2.25^2) (i) P(X>45) =P(Z> (45-42)/2.25) =P(Z>1.3333) = 1 - 0.9082 【Check your normal table!】 = 0.0918 240*0.0918 = 22.03 So 9.18% of the days would the price be over $45. There would be 22 days which the price be over $45. (ii) 6th highest day => 6/240 = 0.0250 of the days will be higher Let t be the required price, then P(X>t) = 0.0250 P(Z> (t-42)/2.25) = 1 - 0.9750 (t-42)/2.25 = 1.96 【Check your normal table!】 t = 42 + 1.96*2.25 = 46.41 The required price is $46.41 2012-12-04 09:08:06 補充： 240天內，會有2.5%的日子，股價比「第六高股價的日子」更高
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其他解答:6th highest day => 6/240 = 0.0250 of the days will be higher 這問這是什麼意思??謝謝
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