MATLAB: Show probabilities (-inf+inf, -3dev-3dev and so on….)

Question

show probabilities (-inf+inf, -3dev-3dev and so on….)

>> mu = 12.5;

sigma = 3.75;

xs = [0:.01:25];

ys = normpdf(xs, mu, sigma);

clf;

plot(xs, ys);

Follow with the mean and std

Answer 1

"Integrating pdf" and "probability ... in given level ranges" sounds like the teacher wants you to use the cdf to get the cumulative probability between a range of values. E.g., maybe this is what is being asked:

>> mu = 12.5;
>> sigma = 3.75;
>> pd = makedist('Normal','mu',mu,'sigma',sigma); % Make a Normal pdf
>> cdf(pd,inf) - cdf(pd,-inf) % the integrated probablility between -inf and +inf
ans =
     1
>> cdf(pd,mu+3*sigma) - cdf(pd,mu-3*sigma) % the integrated probablity between mu-3sigma and mu+3sigma
ans =
    0.9973