PubH 6002
QUIZ 2 Answer Key
Biostatistical Applications for Public Health
George Washington University
This Document Description:
Complete PubH 6002: Biostatistical
Applications for Public Health Quiz 2 Answer
Key (MCQs with fully worked solutions)
, PubH 6002: Biostatistical Applications for Public Health
Quiz 2 - Key
Student Name: _________________________
Instructions: This quiz consists of 11 MC questions. While this quiz is designed to take 35
minutes, you have 2 hours to complete it. Work individually! You may use your own formula
sheets containing relevant hand-written notes as well as a standard or scientific calculator. To
receive full credit, you must show all of your work. Good luck!
1. Based on data from the National Health Survey, the systolic blood pressures (SBP) in the
population of women aged 18 to 24 are normally distributed with a mean of 114.8 mm Hg
and a standard deviation of 13.1 mm Hg. Hypertension is commonly defined as a SBP above
140 mm Hg. If 4 different women between the ages of 18 and 24 are randomly selected, what
is the probability that their mean SBP is greater than 140 mm Hg? (5 points)
- We are given the following information:
o SBP are normally distributed,
o population mean μ = 114.8, and
o population standard deviation σ = 13.1.
a. 3.85
b. 1.25
c. 0.9999
d. 0.4999
e. 0.0001
- We are asked to find P(Xbar > 140). Use the CLT because we are dealing with a sample
of 4 women where the original population has a normal distribution with σ known.
- Apply the formula z = (xbar – μ)/(σ/√n), and use the z-table to find the correct
probability.
- P(Xbar > 140) = P(Z > (140 – 114.8)/(13.1/√4) = P(Z > 3.85) = 0.0001 (column B).
- So, the probability that their mean SBP is greater than 140 mm Hg is 0.0001.
For questions 2-5, refer to the following information: A study is conducted to test the
hypothesis that people with glaucoma have higher than average blood pressure. The study
includes 30 people with glaucoma whose mean SBP is 140 mm Hg with a standard deviation of
25 mm Hg. The distribution of SBP appears to be bell-shaped. You need to construct a 95%
confidence interval for the true mean SBP among people with glaucoma. To help you do so,
answer each of the following questions.
- We are given the following information.
o n = 30
o SBP are bell-shaped (so approximately normally distributed)
o sample mean xbar = 140
o sample standard deviation s = 25
QUIZ 2 Answer Key
Biostatistical Applications for Public Health
George Washington University
This Document Description:
Complete PubH 6002: Biostatistical
Applications for Public Health Quiz 2 Answer
Key (MCQs with fully worked solutions)
, PubH 6002: Biostatistical Applications for Public Health
Quiz 2 - Key
Student Name: _________________________
Instructions: This quiz consists of 11 MC questions. While this quiz is designed to take 35
minutes, you have 2 hours to complete it. Work individually! You may use your own formula
sheets containing relevant hand-written notes as well as a standard or scientific calculator. To
receive full credit, you must show all of your work. Good luck!
1. Based on data from the National Health Survey, the systolic blood pressures (SBP) in the
population of women aged 18 to 24 are normally distributed with a mean of 114.8 mm Hg
and a standard deviation of 13.1 mm Hg. Hypertension is commonly defined as a SBP above
140 mm Hg. If 4 different women between the ages of 18 and 24 are randomly selected, what
is the probability that their mean SBP is greater than 140 mm Hg? (5 points)
- We are given the following information:
o SBP are normally distributed,
o population mean μ = 114.8, and
o population standard deviation σ = 13.1.
a. 3.85
b. 1.25
c. 0.9999
d. 0.4999
e. 0.0001
- We are asked to find P(Xbar > 140). Use the CLT because we are dealing with a sample
of 4 women where the original population has a normal distribution with σ known.
- Apply the formula z = (xbar – μ)/(σ/√n), and use the z-table to find the correct
probability.
- P(Xbar > 140) = P(Z > (140 – 114.8)/(13.1/√4) = P(Z > 3.85) = 0.0001 (column B).
- So, the probability that their mean SBP is greater than 140 mm Hg is 0.0001.
For questions 2-5, refer to the following information: A study is conducted to test the
hypothesis that people with glaucoma have higher than average blood pressure. The study
includes 30 people with glaucoma whose mean SBP is 140 mm Hg with a standard deviation of
25 mm Hg. The distribution of SBP appears to be bell-shaped. You need to construct a 95%
confidence interval for the true mean SBP among people with glaucoma. To help you do so,
answer each of the following questions.
- We are given the following information.
o n = 30
o SBP are bell-shaped (so approximately normally distributed)
o sample mean xbar = 140
o sample standard deviation s = 25
