Answer:
87.26 mm Hg is the reading that represents the 80th percentile of the distribution.
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 78 mm Hg
Standard Deviation, σ = 11 mm Hg
We are given that the distribution of diastolic blood pressure is a bell shaped distribution that is a normal distribution.
Formula:
[tex]z_{score} = \displaystyle\frac{x-\mu}{\sigma}[/tex]
We have to find the value of x such that the probability is 0.80
P(X < x)
[tex]P( X < x) = P( z < \displaystyle\frac{x - 78}{11})=0.8[/tex]
Calculation the value from standard normal z table, we have,
[tex]P(z < 0.842) = 0.8[/tex]
[tex]\displaystyle\dfrac{x - 78}{11} = 0.842\\\\x = 87.262 \approx 87.26[/tex]
87.26 mm Hg is the reading that represents the 80th percentile of the distribution.