Yahoo Answers: Answers and Comments for F.3 Maths [數學]
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From kanam
enUS
Sun, 11 Mar 2007 14:55:47 +0000
3
Yahoo Answers: Answers and Comments for F.3 Maths [數學]
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https://answers.yahoo.com/question/index?qid=20070311000051KK02616
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From Brian Lui: The height of the removed portion of the cone ...
https://answers.yahoo.com/question/index?qid=20070311000051KK02616
https://answers.yahoo.com/question/index?qid=20070311000051KK02616
Sun, 11 Mar 2007 22:34:33 +0000
The height of the removed portion of the cone = h cm
h : (h+7) = 3 : 4
h = 21
The height of the complete cone = 21 + 7 = 28 cm
(a)
Volume of frustum
= ⅓π(4)²(28)  ⅓π(3)²(21)
= 259π/3 cm3
(b)
Time required
= (259π/3) / 15
≈ 18.1 seconds
20070311 22:35:22 補充：
For (b), if it is to be rounded up to the next complete second, then it is 19 seconds.
20070311 22:35:32 補充：
For (b), if it is to be roundedup to the next complete second, then it is 19 seconds.