Answer:
B. The observational study is a cross-sectional study because information is collected at a specific point in time.
Step-by-step explanation:
1) There are three types of Observational Studies: Case-control, cross-sectional and Cohort.
2) Since the researchers collected information from those 1800 adults at a certain time, then we can call it a cross-sectional study. It does not provide solid results since the research was not done over a period to collect further information. We don't know, for example, much more than what that association deeply mean.
3) If we wonder more, then the researchers would have to track those adults over a given period, i.e. a Cohort would be necessary.
4) Moreover, it's not "retrospective" for virtually every question, always makes us look back somehow, and it does not categorize a kind of observational study.
First, note that 
Then use the formula for the sum of perfect cubes:
Therefore,
The quadratic trinomial 
couldn't be factored anymore, so the expression 
has two factors 
and 
Answer: correct choice is A.
Answer:
15 is 40% of 37.5
Step-by-step explanation:
Answer:
Step-by-step explanation:
Answer:
i. terms = 5xy(z)^2 , -3zy
coefficient = 5 and -3
ii. terms = 1 , X ,x^2
coefficient = 1 , 1
iv. terms = 3 , -pq , qr, -rp
coefficient = -1 ,1 , -1
v. terms = X/2 , y/2 , -xy
coefficient= 1/2 ,1/2 and -1
