The table above shows that the scores of a group of students in a test. If the average score is 3.5, find the value of x
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Correct Answer: Option B
Explanation:
\(mean=\frac{60+5x}{18+x}\\3.5=\frac{60+5x}{18+x}\\\frac{7}{2}=\frac{60+5x}{18+x}\)
7(18+x) = 2(60+5x)
126 + 7x = 120 + 10x
10x - 7x = 126 - 120
3x = 6
x = 2
\(mean=\frac{60+5x}{18+x}\\3.5=\frac{60+5x}{18+x}\\\frac{7}{2}=\frac{60+5x}{18+x}\)
7(18+x) = 2(60+5x)
126 + 7x = 120 + 10x
10x - 7x = 126 - 120
3x = 6
x = 2