Question

a diver begins at 140 feet below sea level. she descends at a steady rate of 7 feet per minute for 4.5 minutes. then, she ascends 112.2 feet. what is her current depth?
-549.3 feet
-59.3 feet
59.3 feet
549.3 feet

Explanation:

Step1: Calculate the distance descended

The diver descends at 7 feet per minute for 4.5 minutes. So the distance descended is $7\times4.5 = 31.5$ feet.

Step2: Initial depth and new depth after descending

The initial depth is -140 feet (below sea level). After descending 31.5 feet, the depth becomes $-140 - 31.5=-171.5$ feet.

Step3: Depth after ascending

Then she ascends 112.2 feet. So the current depth is $-171.5 + 112.2=-59.3$ feet.

Answer:

-59.3 feet (corresponding to the option: -59.3 feet)