690
12×36 + 258 = 690 For extending to 20 characters
Answer: 86.64%
Step-by-step explanation:
Let x be a random variable that represents the diameter of metal samples.
Given : Population mean : 
Standard deviation: 
Specified tolerance on the diameter is 0.75 mm.
i.e. range of diameter = 10-0.75< x <10+0.75 = 9.25< x< 10.75
Formula to find the z-score corresponds to x: 
At x= 0.75, 

Using standard normal table for z-value,
P-value : 
∴ Percentage of samples manufactured using this process satisfy the tolerance specification = 86.64%
So we have the system of equations:

equation (1)

equation (2)
To use substitution, we are going to solve for one variable in one of our equations, and then we are going to replace that value in the other equation:
Solving for

in equation (2):



equation (3)
Replacing equation (3) in equation (1):






equation (4)
Replacing equation (4) in equation (3):



We can conclude that the solution of our system of equations is <span>
(7/5, 21/10)</span>