APFIVE Sampling Distribution of the Sample Mean
The life expectancy of naked mole rats is normally distributed with $$\mu = 21$$ years and $$\sigma = 3$$ years. If a random sample of $$n = 40$$ rats is taken, what is the probability that the sample mean, $$\bar{x}$$, is between $$20$$ and $$22$$ years?
A
$$0.900$$
B
Calculation error may lead to a value around $$0.97$$, but the correct standard error gives approximately $$0.965$$.
C
$$0.500$$
D
$$0.965$$
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