Question

In a certain county in New York state, the mean monthly utility bill per household is $295 with a standard deviation of $30. The monthly bill per household is normally distributed. If a random sample of 25 households is selected from this county, what is the probability that the sample mean monthly utility bill will be more than $290? Give your answer to four decimal places. [a]

Answer 1

Using

Given$\begin{gathered} x=290 \\ \mu=295 \\ \sigma=30 \end{gathered}$Solution$\begin{gathered} Z=\frac{290-295}{30} \\ \\ Probabilityofx>290:0.56618 \end{gathered}$The final answer