The Diaz family went on a road trip for vacation. The table includes a cumulative chart of the time they traveled compared to the distance they drove. Over which interval was their average speed the fastest: [0,4], [4,7], [7,9], or [9,12]? Explain your reasoning in 1–2 sentences.
To determine the interval over which their average speed was the fastest, we need to find the steepest slope on the cumulative chart. Since slope represents speed, we can observe that the steepest slope occurs over the interval [0,4]. This means their average speed was the fastest during this interval.
