Final answer:
The y-intercept of Claudia's graph is 9°C, which represents the initial temperature of the substance. The y-intercept can be calculated using the equation of a line and substituting the values of x and y from one of the points on the line. The y-intercept of Claudia's graph is 9°C.
Step-by-step explanation:
The y-intercept of Claudia's graph is 9°C. The y-intercept represents the initial temperature of the substance at the start of the experiment when time is 0. In this case, it represents the original temperature of the substance, which is 9°C.
To calculate the y-intercept of a linear equation, we can use the formula y = mx + b, where m is the slope and b is the y-intercept. Since the temperature increases by 2°C each hour, the slope of the line is 2. Therefore, the equation of the line is y = 2x + b. To find b, we substitute the values of x and y from one of the points on the line. For example, when x = 0 (representing the start of the experiment), y = 9 (the initial temperature). Substituting these values into the equation and solving for b, we get b = 9. Hence, the y-intercept of Claudia's graph is 9°C.