Question

1- Assume that systolic blood pressure of Australian males is Normally distributed with a mean of 113.8 mmHg and a standard deviation of 10.8 mmHg.

What proportion of the male population has a blood pressure over 120 mmHg?

Select one:

a. 28%

b. 57%

c. 5%

d. 72%

2-In a hypothetical population, the age-standardised incidence of liver cancer is 9.5 cases per 100,000 population. Excessive alcohol consumption is a risk factor for development of liver cancer, with consumption of alcohol exceeding lifetime alcohol risk guidelines among an estimated 38% of the hypothetical population.

The incidence of liver cancer was 22.2 cases per 100,000 population among those that drank excessively (lifetime consumption) and the incidence of liver cancer was 1.7 cases per 100,000 population among those who did not report excessive lifetime risky alcohol consumption.

What is the increased risk of liver cancer that can be attributed to excessive alcohol consumption among those who drink excessively?

Select one:

a. 82.1% of the cases of liver cancer in those who drink excessively can be attributed to excessive consumption of alcohol.

b. 20.5 cases of liver cancer per 100,000 population in those who drink excessively can be attributed to excessive consumption of alcohol.

c. 92.3% of the cases of liver cancer in the population can be attributable to excess drinking

d. 7.8 cases of liver cancer per 100,000 population are attributed to excessive drinking

3-The following are the blood plasma volumes from 10 healthy males:

3.01 3.20 3.17 3.27 2.54 3.31 3.05 2.80 2.70 3.59

Calculate the mean, standard error of the mean and the 95% confidence interval for the mean.

Select one:

a. 3.06, 0.099, (2.80 to 3.27)

b. 3.06, 0.099, (2.84 to 3.29)

c. 3.06, 0.314, (2.80 to 3.27)

d. 3.06, 0.314, (2.54 to 3.59)

4- Question text

The prevalence of smoking among the general population is 17%. A study was conducted to investigate the association between smoking and development of dementia among a cohort of 3000 people aged 65-84 years, free of dementia at the start of follow-up. Of them 260 were diagnosed with dementia over the follow-up period, 20% of whom reported smoking at baseline. A total of 2549 participants did not report any history of smoking.

What proportion of dementia could be prevented in the population if the risk factor of smoking was eliminated?

Select one:

a. 5.3%

b. 12.0%

c. 6.6%

d. 5.8%

Answer 1

1)

µ =    113.8                  
σ =    10.8                  
                      
P ( X ≥   120.00   ) = P( (X-µ)/σ ≥ (120-113.8) / 10.8)              
= P(Z ≥   0.57   ) = P( Z <   -0.574   ) =    0.28 or 28%

3)

sample std dev ,    s = √(Σ(X- x̅ )²/(n-1) ) =   0.3143
Sample Size ,   n =    10
Sample Mean,    x̅ = ΣX/n =    3.0640

Level of Significance ,    α =    0.05          
degree of freedom=   DF=n-1=   9          
't value='   tα/2=   2.262   [Excel formula =t.inv(α/2,df) ]      
                  
Standard Error , SE = s/√n =   0.3143   / √   10   =   0.0994
margin of error , E=t*SE =   2.2622   *   0.0994   =   0.2249
                  
confidence interval is                   
Interval Lower Limit = x̅ - E =    3.06   -   0.224859   =   2.8391
Interval Upper Limit = x̅ + E =    3.06   -   0.224859   =   3.2889

So, answer is

b. 3.06, 0.099, (2.84 to 3.29)