Finding the volume of an eraser using water displacement method.

To find the volume of the eraser using the water displacement method, we use the formula:

$$
V = V_f - V_i
$$

Where:
- $ V $ is the volume of the eraser,
- $ V_f $ is the final volume of water (after the eraser is submerged),
- $ V_i $ is the initial volume of water (before the eraser is added).

Step 1: Read the initial volume ($ V_i $)

From the left graduated cylinder:
- The water level is at 8 mL.

So, $ V_i = 8 \text{ mL} $

Step 2: Read the final volume ($ V_f $)

From the right graduated cylinder (with the eraser submerged):
- The water level rises to 15 mL.

So, $ V_f = 15 \text{ mL} $

Step 3: Calculate the volume of the eraser

$$
V = V_f - V_i = 15 \text{ mL} - 8 \text{ mL} = 7 \text{ mL}
$$

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Final Answer:

$$
V = 15 - 8 \\
V = 7 \text{ mL}
$$

✔ So, the volume of the eraser is 7 mL.