Question

this graph shows how the accuracy of nellies watch is related to how long its been since she last set it.
accuracy of nellies watch
how far behind is nellies watch if she last set it 2 days ago?
5 seconds 5.5 seconds 2.5 seconds 6.5 seconds

Explanation:

Step1: Analyze the graph's slope and intercept

The graph is a linear line. Let's assume the equation of the line is \( y = mx + b \), where \( y \) is seconds behind, \( x \) is days since last set, \( m \) is the slope, and \( b \) is the y-intercept. From the graph, when \( x = 0 \), \( y = 1.5 \) (approximate y-intercept). The slope \( m \) can be calculated from two points. Let's take (0, 1.5) and (4, 10). The slope \( m=\frac{10 - 1.5}{4-0}=\frac{8.5}{4} = 2.125\) (approximate). But maybe a better way is to look at the grid. Each day, how much does it increase? From x=0 (y=1.5) to x=2, let's see the y-value. Alternatively, maybe the line passes through (0,1.5) and (2, 5.5)? Wait, no, let's check the options. The options are 5, 5.5, 2.5, 6.5. Wait, maybe the y-intercept is 1.5, and the slope is 2 (approximate). So for x=2, \( y=2\times2 + 1.5=5.5 \)? Wait, no, maybe the graph: when x=0, y is 1.5 (between 1 and 2), x=1, y is around 3.5, x=2, y is around 5.5? Wait, the options include 5.5. Let's re - evaluate.
Wait, maybe the line has a y - intercept of 1.5 and a slope of 2. So the equation is \( y = 2x+1.5 \). When \( x = 2 \), \( y=2\times2 + 1.5=5.5 \). So the answer should be 5.5 seconds.

Answer:

5.5 seconds