標題:

中三數學問題求幫忙

發問:

Measures of Central Tendency1.The average weight of 14 girls is 54 kg.If the average weight of the whole class is65.05 kg,find the average weight of boys in the class.2.Stephen' s examination report shows that the average mark of 8 subjects is 75.5.However,he finds that 2 of the subject marks are... 顯示更多 Measures of Central Tendency 1.The average weight of 14 girls is 54 kg.If the average weight of the whole class is 65.05 kg,find the average weight of boys in the class. 2.Stephen' s examination report shows that the average mark of 8 subjects is 75.5. However,he finds that 2 of the subject marks are wrong.The mark of Chinese language should be 80 instead of 70 and the the marks of Mathematics should be 92 instead of 90.Find the new average mark.

最佳解答:

1. One of the information is missing. The number of the boys or the whole class should be given. Otherwise, no answers. Let x be the number of students in whole class y be the average weight of the boys [(65.05 - 54)* 14 + 65.05 (x-14)]/(x-14)=y (154.7+65.05x-910.7)/(x-14)=y (65.05x-756)/(x-14)=y you can substitude the number of whole class, and calcalate it. 2. (8*75.5 + 10 +2)/8 =77marks

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