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.
Answer:
184 in²
Step-by-step explanation:
Given :
Width, w = 6 inches
Length, l = 10 inches
Height, h = 2 inches
To obtain how much wrapping paper is needed ; we take the surface area of the box
Surface area = 2(lw + lh + wh)
Surface area = 2((6*10) + (6*2) + (10*2))
Surface area = 2(60 + 12 + 20)
Surface area = 2(92)
Surface area = 184 in²
The amount of wrapping paper needed = 184 in²
You can set up an equation based off of the information given:
x represents the unknown number
3/5x - 1 = 23
add 1 to both sides to isolate the 3/5x
3/5x = 24
divide both sides by 3/5 to solve for x
x = 120/3
120/3 can be simplified into 40
Final answer: x = 40

Negative multiply negative = Positive
Negative multiply positive = negative

Thus the answer is -4a + 16b - 12c - 12d.