Question 1181631
z=(x-mean)/sd
for one individual, z > (17.6-18)/3.2=-0.4/3.2 or -0.125.
the probability z > -0.125 is 0.5497
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for the mean's being > 17.6 the sd becomes 3.2/sqrt(73)=0.3745
z >(17.6-18)*sqrt(73)/3.2=-1.068
the probability z > -1.068 is 0.8572

The distribution of the samples of 73 is much narrower, so that the same value to the left o the mean is much closer to the left side of the distribution, and since the probability we want is to the right of that, that probability is more.