Ιf the average test score of four students is 85, which of the following scores could a fifth student receive such that the average of all five scores is greater than 84 and less than 86?
Indicate all such scores:
A. 88
B. 86
C. 85
D. 83
E. 80
Λύση (Α, B, C, D):
Average = [katex]\dfrac{Sum of terms}{Number of terms}[/katex]
[katex]\Rightarrow[/katex]Sum = Average * Number of terms
Άρα αν x είναι το πιθανό σκορ του πέμπτου μαθητή :
84 < < 86 [katex]\Rightarrow[/katex]
420 < 340 + x <430 [katex]\Rightarrow[/katex]
80 < x < 90
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