Answer:
[tex]c = 11[/tex]
Step-by-step explanation:
Given
[tex]Cars\ Sold:-: 8; 9; 12; c[/tex]
Required
What value of c makes the mean = 10
Mean is calculated as
[tex]Mean = \frac{\sum x}{n}[/tex]
In this case;
Mean = 10 and n = 4;
So, we have:
[tex]10 = \frac{8+ 9 + 12 + c}{4}[/tex]
[tex]10 = \frac{29+ c}{4}[/tex]
Multiply both sides by 4
[tex]10 * 4 = 29 + c[/tex]
[tex]40 = 29 + c[/tex]
Solve for c
[tex]c = 40 - 29[/tex]
[tex]c = 11[/tex]