Answer: About 95% of her phone bills are between $36 and $60.
Explanation:
If population is normally distributed , then by Empirical rule about 95% of the population lies within 2 standard deviations from mean.
Given: The amount of Jen's monthly phone bill is normally distributed with a mean of $48 and a standard deviation of $6.
Then, by Empirical rule
About 95% of her phone bills are between $(48 -2(6)) and $(48 +2(6))
i.e. About 95% of her phone bills are between $36 and $60.
Hence, About 95% of her phone bills are between $36 and $60.