Answer:
D. By adding the vectors

Explanation:
Given
Represent the velocity of the river current as VR

Represent the velocity of the boat as VB

Required
How to calculate the velocity of boat relative to river current
From the question, we understand that both move in the same direction.
So, the relative velocity V is calculated as:



Notice that the both velocities are added together to get the relative velocities.
This is so because they both move in the same direction
<em>From the list of given options, only option D is correct.</em>
<u>ANSWER:</u>
The correct option is A: The country was in recession.
<u>EXPLANATION:</u>
- When Obama became the president in 2009, the country was in great recession and financial crisis. Obama's main challenge was to fight and do away with the recession of 2008 that had hit the country hard.
- Obama was successful in fighting this recession. He not only announced an economic stimulus package for the country but also cut taxes and funded public works.
- By investing in the country, Obama was able to get the country out of recession in a few years.
Chief justice writes the court's opinion.
Chief justice presides also over the trial in the Senate. Also has a ceremonial duty of administering the oath of office of the President.
Answer:
B). A Cross-sectional research design.
Explanation:
A cross-sectional research design is demonstrated as a kind of observation study that involves the study and analysis of a representative subset from the population at a particular point of time.
In the given example, Tucker is employing 'cross-sectional research design' as he selects a representative subset('a group of 5-year-olds, a group of 10-year-olds, and a group of 15-year old) from the population at the same time for study and analysis(by interviewing them) . This implies that Tucker adopts a '<u>cross-sectional research design</u>.'