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
-
A.
1 -
B.
2 -
C.
3 -
D.
4
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