A scientist uses a submarine to study ocean life.
A She begins at sea level, which is an elevation of o feet.
B She travels down 21.1 feet.
C She then ascends 19.1 feet.
D Next, she travels down a second time, 80.7 feet.
How many feet must she now ascend to get back to sea level?
The correct answer and explanation is:
To determine how many feet the scientist must ascend to return to sea level, we can break down her movements step by step.
- Starting at sea level (0 feet):
The scientist begins at sea level, which is an elevation of 0 feet. - Travels down 21.1 feet:
When the scientist travels down 21.1 feet, her new elevation is: 0−21.1=−21.1 feet0 – 21.1 = -21.1 \text{ feet} So, she is now 21.1 feet below sea level. - Ascends 19.1 feet:
When the scientist ascends 19.1 feet, her new elevation is: −21.1+19.1=−2.0 feet-21.1 + 19.1 = -2.0 \text{ feet} This means she is now 2 feet below sea level. - Travels down again by 80.7 feet:
The scientist then travels down another 80.7 feet, so her new elevation is: −2.0−80.7=−82.7 feet-2.0 – 80.7 = -82.7 \text{ feet} This puts her 82.7 feet below sea level. - To return to sea level:
To get back to sea level (0 feet), she must ascend by the same amount that she is below sea level. Since she is at an elevation of -82.7 feet, she must ascend 82.7 feet to reach sea level.
Thus, the correct answer is that the scientist must ascend 82.7 feet to return to sea level.