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
Attached Figure / Diagram
A
1
B
2
C
3
D
4
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
\(mean=\frac{60+5x}{18+x}\\3.5=\frac{60+5x}{18+x}\\\frac{7}{2}=\frac{60+5x}{18+x}\)
7(18+x) = 2(60+5x)
126 + 7x = 120 + 10x
10x - 7x = 126 - 120
3x = 6
x = 2
Source: Myschool Past Questions Archive (Record #8609)