1. **State the problem:** We have height data points at times 0, 1, 2, and 3 hours with heights 16, 58, 4, and 38 meters respectively. 2. **Goal:** Determine the best value for $A$ to use as the step size on the height axis for the graph scale. 3. **Analyze the data:** The minimum height is $4$ m and the maximum height is $58$ m. 4. **Choosing $A$:** The step size $A$ should be a positive number that divides the range of heights nicely and allows clear labeling. 5. **Calculate the range:** $$\text{Range} = 58 - 4 = 54$$ 6. **Consider common step sizes:** Factors of 54 include 1, 2, 3, 6, 9, 18, 27, 54. 7. **Best scale choice:** A step size of $10$ is common for graphs, but 10 does not divide 54 evenly. Instead, $6$ is a good choice because it divides 54 evenly and is not too small or large. 8. **Check scale labels:** Starting from 0, labels would be 0, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60 which covers the max height 58 well. 9. **Conclusion:** The best value for $A$ is $6$ meters for clear and even scaling on the height axis. **Final answer:** $A = 6$