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发表于 17-2-2013 20:44:51|来自:新加坡
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each teacher plant 3 trees, each pupil plants 2/3 trees.
Teachers: 000000000 000000000 000000000 000000000 000000000 000000000 000000000...
Pupils: 00 00 00 00 00 00 00 ...
Each unit 0 = 1/3 tree
By adding a 0000000(7'0's to each pupil, each of them can plant as many trees as teachers. in total they will plant 9 x 360 = 3240 units. The fact is, there is a total of 520 x 3 = 1560 units.
=1680 units, this diffence is due to adding 7 units to each pupil.
1680 / 7 = 240, there are 240 pupils |
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