一架电梯的最大载重是1000千克. 现有13位 “重量级”的乘客要搭乘电梯，已知其中11位先生的平均体重是80千克，2位女士的平均体重是70千克，请问他们能否一起安全地搭乘这架电梯？他们的平均体重是多少千克？
小飞的解答：11位先生的总体重=80×11=880 (千克) 2位女士的总体重=70×2=140(千克) 13位乘客的总体重=880+140=1020(千克) 因为总体重超过了电梯的最大载重，所以他们不能一起安全地搭乘，平均体重是(80+70)÷2=75(千克)
你怎样评价小飞的解答？只有在什么情况下才可以采取这种策略求平均数？
解：小飞的解答中，求平均体重是错的
13位乘客的平均体重为 1 020÷l3≈78.5(千克).
只有当两组数据的数据个数相同时. 这种策略才可行.
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| Some people think that all wild animals are dangerous. But in fact, very few of them will 1 a man if he leaves them alone. If you meet a lion or an elephant, I guess you will 2 ; but even a lion will avoid (躲避) a man if it is not very 3 . Lions and tigers only kill and eat men when they have grown too old and too weak to catch their usual 4 , such as deer and 5 small animals. If you see a wild elephant, perhaps you will be 6 . However, elephants usually run away at once if you don't attack them. Some animals get very frightened if they only smell a man, some stand and look at him for a moment 7 they run away, some take no notice at all but walk away 8 in another direction. Wild animals only attack 9 when they are afraid that people want to harm their 10 , or when the hunters shoot at them and make them angry. | ||||
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