Sampling Distribution of the Sample Mean

Question

The life expectancy of naked mole rats is normally distributed with a mean of $$\mu = 21$$ years and a standard deviation of $$\sigma = 3$$ years. For a random sample of $$n = 40$$ rats, what is the probability that the sample mean life expectancy, $$\bar{x}$$, is between 20 and 22 years?

Accepted Answer

$$0.965$$

Answer

Calculation error may lead to a value around $$0.97$$, but the correct standard error gives approximately $$0.965$$.

Answer

$$0.900$$

Answer

$$0.500$$

Sampling Distribution of the Sample Mean

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