甲水龍頭注滿六桶水需時 39 分鐘，乙水龍頭注滿同三桶水需時 15 分鐘。如果兩個水龍頭同時開動 2分鐘，可注滿多少桶水？
數學知識交流(1)
2011-11-17 3:34 am
回答 (3)
2011-11-17 3:41 am
✔ 最佳答案
您好，我是 lop，高興能解答您的問題。如果兩個水龍頭同時開動 2分鐘，可注滿：
2 ÷ (39÷6) + 2 ÷ (15÷3)
= 2 ÷ 6.5 + 2 ÷ 5
= 4/13 + 2/5
= 46/65 桶
~ 0.7077 ( cor. to 4 dec. places )
答：如果兩個水龍頭同時開動 2分鐘，可注滿 46/65 桶水。
2011-11-17 20:56:45 補充：
(2)
三個水龍頭需同時開動：
= 16 ÷ ( 5 ÷ 40 + 4 ÷ 16 + 2 ÷ 12 )
= 16 ÷ ( 1/8 + 1/4 + 1/6 )
= 16 ÷ ( 3/24 + 6/24 + 4/24 )
= 16 ÷ 13/24
= 16 × 24/13
= 384/13 分鐘
答：三個水龍頭需同時開動 384/13 分鐘，才可注滿多少 16 桶水。
參考: Hope I Can Help You ^_^ ( From me ), Hope I Can Help You ^_^ ( From me )
2011-11-17 8:18 pm
1.
try to figure out how full of box per minute (because it gives the requirement of 2 minutes)
甲= 6/39 box/minute
乙= 3/15 box/minute
2mins x (6/39 + 3/15) = 2 x 23/65 = 46/65 box
2.
try to figure out how full of box per minute (same principle as 1)
甲= 5/40 box/minute
乙= 4/16 box/minute
丙= 2/12 box/minute
total (5/40 + 4/16 + 2/12) = 13/24 box/minute for 3 taps together
16 box / (13/24) = 384/13 minutes required for 3 taps together
try to figure out how full of box per minute (because it gives the requirement of 2 minutes)
甲= 6/39 box/minute
乙= 3/15 box/minute
2mins x (6/39 + 3/15) = 2 x 23/65 = 46/65 box
2.
try to figure out how full of box per minute (same principle as 1)
甲= 5/40 box/minute
乙= 4/16 box/minute
丙= 2/12 box/minute
total (5/40 + 4/16 + 2/12) = 13/24 box/minute for 3 taps together
16 box / (13/24) = 384/13 minutes required for 3 taps together
2011-11-17 5:52 am
甲水龍頭注滿一桶水需時
40/5
8
乙水龍頭注滿一桶水需時
16/4
4
丙水龍頭注滿一桶水需時
12/2
6
3個水龍頭同時開動8分鐘
(8/8)(1) + (8/4)(1) + (8/6)(1)
=1+2+4/3
=13/3
16/(13/3)(8)
=16(3/13)(8)
=(48/13)(8)
=384/13分鐘
40/5
8
乙水龍頭注滿一桶水需時
16/4
4
丙水龍頭注滿一桶水需時
12/2
6
3個水龍頭同時開動8分鐘
(8/8)(1) + (8/4)(1) + (8/6)(1)
=1+2+4/3
=13/3
16/(13/3)(8)
=16(3/13)(8)
=(48/13)(8)
=384/13分鐘
收錄日期: 2021-04-11 18:48:14
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20111116000051KK00627