random variable with normal distribution
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Tony on 11 Nov 2013
Answered: Roger Stafford on 11 Nov 2013
Hello, here is the problem:
A random variable obeys a normal distribution. It has a mean value equal to 100 and a standard deviation equal to 3. Find the probability that:
x < 98
98 < x < 104
x > 98
I have a slight idea i know how to find mean using mean(x) and randn(x) for some random number but no idea how to tie them together.
thank you for your time
Image Analyst on 11 Nov 2013
If you want to do it empirically (like Monte Carlo), you can use this:
numberOfNumbers = 1000000; % Whatever number you want.
% From the help:
randomNumbers = 100 + 3 * randn(1, numberOfNumbers);
% Count number less than 98
count = sum(randomNumbers < 98)
fprintf('The number of numbers less than 98 = %g%%\n',...
count * 100 / numberOfNumbers);
Repeat for other ranges.
Roger Stafford on 11 Nov 2013
The Statistics Toolbox function 'normcdf' is just what you need.
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