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[maths] probability [20marks]
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3. The alkalinity level of water specimens (in milligrams per liter) collected from the Rambler Channel has a mean of 50 and a variance of 23.04. Assume that the distribution of alkalinity levels is approximately normal.3a. What is the probability that a water specimen collected from the channel has an... 顯示更多 3. The alkalinity level of water specimens (in milligrams per liter) collected from the Rambler Channel has a mean of 50 and a variance of 23.04. Assume that the distribution of alkalinity levels is approximately normal. 3a. What is the probability that a water specimen collected from the channel has an alkalinity level above 55 milligrams per liter? 3b. What is the probability that a water specimen collected from the harbor has an alkalinity level between 44 and 60 milligrams per liter? 3c. 75% of the specimens have an alkalinity level above what value? BY asodmokasmko 更新: 煩請高手列下步驟 更新 2: (a) 個答案 點解我計到0.1492
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3) Let Xmg/L be the alkalinity level of water specimens collected from the Rambler Channel X~N(50,23.04) (a) P(a water specimen collected from the channel has an alkalinity level above 55 milligrams per liter) =P(X>55) =P[Z>(55-50)/sqrt(23.04)] =P(Z>25/24) ~0.3508 (b) P(a water specimen collected from the harbor has an alkalinity level between 44 and 60 milligrams per liter) =P(44
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