Data InsightsGraphs & Tables

Free GMAT Graphs & Tables Practice Question

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Five wind farms in rows; columns: annual output (gigawatt-hours), operating cost (thousands of dollars), turbines, year online. Sortable.
Wind farm	Annual output (GWh)	Operating cost ($000s)	Turbines	Year online
Ridgewind	520	4,160	40	2017
Tallgrass	610	4,880	50	2019
Gale	470	4,230	20	2015
Seacliff	700	4,900	56	2021
Highmoor	430	3,440	25	2014

The table shows five wind farms: the annual electricity output in gigawatt-hours, the annual operating cost in thousands of dollars, the number of turbines, and the year the farm came online. The table can be sorted by any column. For each statement, select Yes if it must be true based only on the data shown; otherwise select No.

(1) From the data shown, it can be determined which wind farm has the lowest operating cost per megawatt-hour of output: . (2) When the wind farms are sorted by annual output from highest to lowest, Gale appears in the bottom row: . (3) The wind farm with the most turbines also produces the most output per turbine: .

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Answer & Explanation

Correct answer

1: Yes · 2: No · 3: No

One statement asks only whether a cost can be determined, one hinges on actually re-sorting, and one builds a per-turbine ratio.

Statement 1 - Yes. Cost per megawatt-hour is annual operating cost divided by annual output. One gigawatt-hour is 1,000 megawatt-hours, so the ratio works out to Ridgewind $8.00, Tallgrass $8.00, Gale $9.00, Seacliff $7.00, Highmoor $8.00 per megawatt-hour. The lowest is Seacliff at $7.00, so the answer can be determined. The statement asks only whether it can be determined, and it can. The trap is to answer No because no such column is shown, or to pick Highmoor for its smallest raw operating cost; the cheapest total is not the cheapest per unit.

Statement 2 - No. Gale is the last row as the table is printed, which is the bait. But the statement asks about the order after sorting by annual output from highest to lowest, and that order is Seacliff 700, Tallgrass 610, Ridgewind 520, Gale 470, Highmoor 430. The bottom row of that sort is Highmoor, the farm with the least output, not Gale. So the statement is false. The trap is to trust the printed order instead of actually re-sorting.

Statement 3 - No. Output per turbine is annual output divided by turbines: Ridgewind 13.0, Tallgrass 12.2, Gale 23.5, Seacliff 12.5, Highmoor 17.2 gigawatt-hours per turbine. The farm with the most turbines is Seacliff at 56, but its 12.5 per turbine is near the bottom; the highest per turbine is Gale, the smallest farm with only 20 turbines. So the statement is false. The trap is to assume that more turbines must mean more output from each one.

The lesson: a cost per unit is computable from two columns, a position claim demands a real re-sort, and a per-turbine figure can invert the turbine-count ranking. Correct answers: Yes / No / No.