Question

the graph shows the amount of sediment, in cm, at the bottom of a lake, built up after varying numbers of years.
sediment levels versus time in a lake
what does the y - intercept of the graph represent?
the original sediment level was 7 centimeters
the sediment increases by 7 centimeters each year.
the sediment increases by 5 centimeters each year.
the original sediment level was 5 centimeters.

Explanation:

The y - intercept of a graph in the form of a linear relationship (like this one, where x is time in years and y is sediment level in cm) occurs when x = 0. At x = 0, the time is 0 years (the start, or original time). So the y - value at x = 0 represents the original sediment level. Looking at the options, we analyze each:

• "The sediment increases by 7 centimeters each year" and "The sediment increases by 5 centimeters each year" refer to the slope (rate of change), not the y - intercept.
• Now, we need to check the y - intercept value. From the graph, when time (x) = 0, the sediment level (y) is 5 cm? Wait, no, wait. Wait, maybe I misread. Wait, the y - intercept: in a graph of sediment (y) vs. time (x, years), when x = 0 (0 years, the original time), the y - value is the original sediment. Let's re - evaluate the options. The first option says original sediment was 7, the last says 5. Wait, maybe the y - intercept is at 5? Wait, no, maybe I made a mistake. Wait, let's think again. The y - intercept is when x = 0 (time = 0 years). So the y - value at x = 0 is the original sediment level. So if the y - intercept is at 5 (when x = 0, y = 5), then the original sediment level was 5 centimeters. So the correct option is "The original sediment level was 5 centimeters."

Answer:

D. The original sediment level was 5 centimeters. (Assuming the options are labeled as A: The original sediment level was 7 centimeters, B: The sediment increases by 7 centimeters each year, C: The sediment increases by 5 centimeters each year, D: The original sediment level was 5 centimeters)