On the real test, Graph questions are presented as one or two statements with blanks in the statements; there are drop-down menus in the blanks to choose your answer.
Flowcharts show a process broken down into steps. In this one, the rectangles all have times associated with them, and the diamonds all have question marks. It must be that the rectangles are the stages, which take time, and the diamonds are the questions that are asked in order to determine the next step. Map out the prompt:
Sample map (yours will likely differ):
Produce 50kg batch chem
▭ = stages, ♢ = decision pts
Time in mins, no wait b/w stages
3/4 no add'l heat; 1/2 need 2nd mix w/ HCL
A batch of this chemical begins the process with Heating at 200K and then moves through the stages until it reaches the last stage, Drying at 150K. There are two possible detours: 1/4 of the batches need the 20-minute Additional heating stage, and 1/2 need to redo the 20-minute HCL mixing stage.
Statement 1: No information is given about the number of batches, so the average cannot be calculated as the total time divided by the total number of batches. Start with the simplest case of a batch that requires neither of the two extra stages. Such a batch would go through Heating at 200K (30 minutes), Sitting (5 minutes), HCL mixing (20 minutes), Filtration (10 minutes), and Drying at 150K (60 minutes). That would take a total of 30 + 5 + 20 + 10 + 60 = 125 minutes. Since some batches will take longer than that, eliminate 120 and 125.
The prompt provides the proportion of batches that go through the additional stages, so use those proportions to figure out the average time added in the extra stages. One-quarter of the batches need to undergo 20 minutes of Additional heating, so that's 1/4 x 20 = 5 extra minutes on average. (You could also figure this out by thinking about four batches, one of which needs extra heating. The average added time is (20 + 0 + 0 + 0) ÷ 4 = 5 minutes.) Similar logic suggests that 1/2 x 20 = 10 extra minutes is added on average by repeating the HCL mixing stage. The overall average time, then, is 125 + 5 + 10 = 140 minutes.
The correct answer for the first blank is 140.
Statement 2: Again, start with the simplest case of a batch that requires no extra stages. Such a batch would go through Heating at 200K, Sitting, HCL mixing, Filtration, and Drying at 150K. That's five stages. How many stages are added to that average by the batches that take longer? Use the same logic from Statement 1: 1/4 of the batches undergo Additional heating, so that's on average 1/4 or 0.25 additional stages, and 1/2 of the batches repeat the HCL mixing stage, so that's another 1/2 or 0.5 additional stages. The average number of stages, then, is 5 + 0.25 + 0.5.
The correct answer for the second blank is 5.75.
