random variable with normal distribution
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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
回答（3 个）
Image Analyst
2013-11-11
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
2013-11-11
0 个投票
The Statistics Toolbox function 'normcdf' is just what you need.
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2013-11-11
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