In 1998 the World Health Organization reported the findings of a major study on the quality of blood pressure monitoring around the world. In its report it stated that for Canada the results for diastolic blood pressure had a mean of 78 mmHg and a standard deviation of 11 mmHg. Assuming that diastolic blood pressure measurements are Normally distributed, the DBP reading that represents the 80th percentile of the distribution is _____.

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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.