Blood pressure is measured in 100 women over the age of 65 who have been diagnos

Question

Blood pressure is measured in 100 women over the age of 65 who have been diagnosed with glaucoma. The results of this study reveal a mean systolic BP of 140 mm Hg and a standard deviation of 15 mm Hg. 1. Assuming a normal distribution, approximately what proportion of women over 65 years of age who have been diagnosed with glaucoma would be expected to have a BP that falls between 110 and 170 mm Hg? 2. The variable “Blood Pressure” is measured at which of the levels of measurement, explain your answer? 3. Suppose that a relationship between the years since diagnosis and BP in these women was also investigated. What type of relationship would a correlation coefficient of 0.76 indicate, and describe the relationship

Explanation / Answer

1)

Mean= 140
sd= 15
n= 100

P(110 < X < 170)
= P(X<170)-P(X<110)

I know that, z = (X-mean)/(sd/sqrt(n))
z1 = (110-140)/15/sqrt(100))
z1=-20.0000
z2 = (170-140)/15/sqrt(100))
z2= 20.0000

hence,
P(110 < X < 170)=
= P(Z<20)-P(Z<-20)
= NORMSDIST(20)-NORMSDIST(-20)
1.0000

2)

Blood pressure is measured by the ratio scale of measurement. It is a continuous variable which is comparable in nature.

3)

The correlation coefficient of 0.76 indicates that there is a strong positive linear relationship between years since diagnosis and BP. That is as the value of years since diagnosis increases, the value of blood pressure also increases.

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