In an exam, he mean mark of the whole class is 85 marks. The dfferences between the marks of 10 students in the class and the mean mark of the whole class are as follows (uni :marks):
3, 10,-2,28,6,0 ,15,-8,-1,9.
What is the mean mark of the 10 students?
Answer : 87.4 marks
點計嫁？
請列式。
Maths Question 急
2009-02-22 3:17 am
回答 (1)
2009-02-22 4:47 am
✔ 最佳答案
The difference "28" in the question should be "-8".
Method 1:
Mean mark of the 10 students
= [85 + (3 + 10 - 2 - 8 + 6 + 0 + 15 - 8 -1 + 9)/10] marks
= [85 + 24/10] marks
= 87.4 marks
Method 2:
The marks of the 10 students are:
85+3, 85+10, 85-2, 85-8, 85+ 6, 85+0, 85+15, 85-8, 85-1, 85+ 9
i.e.
88, 95, 83, 77, 91, 85, 100, 77, 84, 94
Mean marks of the 10 students
= (88 + 95 + 83 + 77 + 91 + 85 + 100 + 77 + 84 + 94)/10 marks
= 874/10 marks
= 87.4 marks
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