Question

Measurements of a number of fittings show that the pitch diameter of the thread is normally distributed with a mean of 8.007 mm and a standard deviation of 0.005 mm. The design specifications require that the pitch diameter be 8 ± 0.01 mm. Estimate the percentage of fittings that will be within tolerance.

Answer 1

Program plan:

• To write a matlab code to find the percentage of fittings that will be within tolerance.

 

Program:

%**********************************************************

%A matlab code is written to estimate the percentage of

%fittings that will be within tolerance.

%**********************************************************

%Declaration of mean

mu=8.007;

%Declaration of standard deviation

sigma=0.005;

%Computes the value

z1=(7.99-mu)/sigma;

%Computes the value

z2=(8.01-mu)/sigma;

%Computes the values of percentage of fittings that will be within tolerance

p=100*(1-erf(z1/sqrt(2))-1+erf(z2/sqrt(2)))/2;

%Displays text

disp('The percent of the fitting that will be within tolerance');

%Displays value

disp(p);

 

Output:

>> Untitled

The percent of the fitting that will be within tolerance

72.5410

The percent of the fitting that will be within tolerance

72.5410