Blood pressure is measured in 100 women over the age of 65 who have been diagnos
ID: 2946219 • Letter: B
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.