Hi, I wanted to get a quick look over for my program see if there were any flaws.. I think it's complete. specifications and program in link thanks..

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I think the only thing i'm missing is the mean of the means (not very difficult but I am feeling lazy after working on this all day)
and the histogram displaying correctly at the moment I'm not sure it would display with the randomly generated values I think it should be simple to input I'm just new to MATLAB.. Thank you :)
Specifications for program below:
1. Generate 100 samples of size 225 random numbers from U(-3,6). For each of these 100 samples calculate the mean.
a) Find the simulated probability that the mean is between 1 and 2.
b) Find the mean of the means.
c) Find the standard deviation of the means.
d) Draw the histogram of the means.
nsamples=100;
samplenum = 1:nsamples;
%setting number of samples and the sample amt. i.e. here there
%is only 1 sample of number 100
n = 225;
%sample size 225
a = 1;
%setting first mean value of 1
b = 2;
%setting second mean value of 2
theProbability = sum(nsamples > a & nsamples < b) / n;
%finding the probability that the mean is between a and b
a + (b-a)*rand()
%gives uniform random values in the interval [a,b]
data = a + (b-a)*rand(1, nsamples);
%setting data values
cMean = mean(data)
%calculating mean of data
cStdDev = std(data)
%calculating standard deviation of data
z = normrnd(-3,6,n,1);
%setting distribution of random numbers U(-3,6) (n)=(U) here
hist(z,-9.75:.5:9.75);
%setting histogram values for x-axis (labeled here as z)
xlim([-10 10]);
%setting x-axis coordinates
title('Generating 100 Samples of Size 225 Simulated U(-3,6) Random Numbers Histogram Question 1 Part d)');
%title of histogram
xlabel('Z');
%labeling x-axis
ylabel('Frequency');
%labeling y-axis

Accepted Answer

Alexandra Harkai
Alexandra Harkai on 29 Nov 2016
The random sample comes from a normal instead of a uniform sample (assuming U stands for uniform). Also all the data you generated is in the (a,b) interval which will give you 1 for question a).
nsamples=100; % number of samples
n = 225; % sample size 225
a = 1;
b = 2;
data = -3+9*rand(nsamples, n); % random 100x225 data sample from a uniform (0,1) distribution
cMean = mean(data, 2); % mean of each sample
answer_a = sum(cMean > a & cMean < b)/nsamples; % how many data means are between a and b
answer_b = mean(cMean);
answer_c = std(cMean, 1);
hist(cMean);
title('Generating 100 Samples of Size 225 Simulated U(-3,6) Random Numbers Histogram Question 1 Part d)'); %title of histogram
xlabel('Z'); %labeling x-axis
ylabel('Frequency'); %labeling y-axis
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