The time-series graph below gives the price (USD) of a gallon of gas each month over the course of a year. Find the time intervals during which gas prices are increasing.
 

• A. Jan-Feb and Jun-Aug
• B. Feb-Dec
• C. Mar-Apr and May-Jun
• D. Feb-Jun and Aug-Dec

Answer: (D)

Verified step by step guidance

1. Step 1: Observe the time-series graph provided. The x-axis represents months (Jan to Dec), and the y-axis represents the price of gas in USD. Each point on the graph corresponds to the price of gas for a specific month.
2. Step 2: Identify the intervals where the graph is increasing. An increasing interval occurs when the price of gas rises from one month to the next, indicated by an upward slope between consecutive points.
3. Step 3: Analyze the graph month by month: From Feb to Jun, the graph shows a consistent upward trend, indicating that gas prices are increasing during this interval. Similarly, from Aug to Dec, the graph again shows an upward trend.
4. Step 4: Note that the graph decreases in price from Jun to Jul and remains flat or decreases slightly in other intervals, which are not considered increasing intervals.
5. Step 5: Conclude that the time intervals during which gas prices are increasing are Feb-Jun and Aug-Dec, based on the upward slopes observed in the graph.