Question

a fish starts at five feet below sea level and then descends eight feet. if sea level is at 0 feet, whats the final depth of the fish? select one of four -3 feet -13 feet 3 feet 13 feet remaining attempts: 1

Explanation:

Step1: Represent initial depth

Below sea level is negative, so initial depth: $-5$ feet.

Step2: Add descent distance

Descends 8 feet (negative direction), so final depth: $-5 + (-8) = -13$? Wait, no—depth is magnitude below sea level. Wait, initial: 5 ft below (so position -5). Descends 8 ft, so new position: $-5 - 8 = -13$ feet (position), but depth is the absolute value? No, wait, the question says "final depth". Wait, sea level is 0, below is negative. Wait, no—depth is how far below, so if position is -13, depth is 13 feet? Wait, no, the options have -13 and 13. Wait, let's re-express:

Starting at 5 feet below sea level: that's a position of $-5$ (since sea level is 0, below is negative). Then descends 8 feet: descending means moving further below, so we subtract 8 (or add -8) to the position. So $-5 + (-8) = -13$ (position). But depth is the distance below sea level, so the depth is 13 feet (since -13 means 13 feet below). Wait, but the options have -13 and 13. Wait, maybe the question is using position as depth (with negative for below). Wait, let's check the options. The options are -3, -13, 3, 13.

Wait, initial: 5 below: -5. Descends 8: so total below: 5 + 8 = 13. So depth is 13 feet. But the option -13 is a position, 13 is depth. Wait, maybe the question is using "depth" as the position (with negative for below). Let's recalculate:

Initial depth (position): -5 (5 below). Then descends 8: so new depth (position): -5 - 8 = -13. So the final depth (position) is -13? But that's a position. Wait, maybe the question is using "depth" as the value with negative for below. So the answer would be -13? No, wait, depth is a positive quantity. Wait, I think I made a mistake. Let's clarify:

Sea level: 0. Below sea level: negative position. Depth is the distance from sea level, so depth = |position|. But the options include -13 and 13. Let's see the calculation again:

Start at 5 feet below: position = -5.

Descends 8 feet: so moves 8 feet further below, so new position = -5 - 8 = -13.

So the position is -13, which means 13 feet below sea level. So the depth (how far below) is 13 feet. But the option 13 is there. Wait, maybe the question is using "depth" as the position (with negative indicating below). So the final depth (position) is -13? No, that doesn't make sense. Wait, let's check the arithmetic again:

5 feet below + 8 feet descended = 13 feet below. So depth is 13 feet. So the answer should be 13 feet. But wait, the option -13 is a position, 13 is depth. Let's check the options again. The options are:

-3 feet

-13 feet

3 feet

13 feet

So initial: -5. Descend 8: -5 - 8 = -13 (position). But depth is 13. Wait, maybe the question is using "depth" as the position (with negative for below). So the final depth (position) is -13? No, that's confusing. Wait, maybe I messed up the sign. Let's think of depth as a positive number when below. So starting at depth 5 (5 below), then descends 8, so depth 5 + 8 = 13. So the answer is 13 feet.

Wait, but let's check the arithmetic with signed numbers. If sea level is 0, below is negative. So initial position: -5. Descending 8 feet: so the change is -8 (since descending is negative direction). So new position: -5 + (-8) = -13. So the position is -13, which is 13 feet below sea level. So the depth (the distance below) is 13 feet. So the answer is 13 feet.

Answer:

13 feet