We know that
• The mean is 250.
,• The standard deviation is 75.
,• The distribution is normal.
To find the number of beds they will have 95% of the time, first, we have to find the z-score with the following formula.
[tex]z=\frac{x-\mu}{\sigma}[/tex]Where,
[tex]\begin{gathered} \mu=250 \\ \sigma=75 \end{gathered}[/tex]We have to find the probability of
[tex]P(z<\frac{x-\mu}{\sigma})=0.05[/tex]Since the complement part of 95% is 5% which is equal to 0.05.
Using the z-core table below, we find that the z-score assigned to 0.050 is -1.6.
Then, we have the equation and solve for x.
[tex]\begin{gathered} \frac{x-250}{75}=-1.6 \\ x-250=-1.6\cdot75 \\ x-250=-120 \\ x=-120+250=130 \end{gathered}[/tex]