Date | November 2021 | Marks available | 1 | Reference code | 21N.1.AHL.TZ0.8 |
Level | Additional Higher Level | Paper | Paper 1 | Time zone | Time zone 0 |
Command term | Interpret | Question number | 8 | Adapted from | N/A |
Question
Juri skis from the top of a hill to a finishing point at the bottom of the hill. She takes the shortest route, heading directly to the finishing point .
Let define the height of the hill above at a horizontal distance from the starting point at the top of the hill.
The graph of the derivative of is shown below. The graph of has local minima and maxima when is equal to and . The graph of intersects the -axis when is equal to , and .
Identify the value of the point where has its maximum value.
Interpret this point in the given context.
Juri starts at a height of metres and finishes at , where .
Sketch a possible diagram of the hill on the following pair of coordinate axes.
Markscheme
A1
[1 mark]
the hill is at its steepest / largest slope of hill A1
[1 mark]
A1A1A1
Note: Award (A1) for decreasing function from to and to and increasing from to ; (A1) for minimum at and max at ; (A1) for starting at height of and finishing at a height of at . If reasonable curvature not evident on graph (i.e. only straight lines used) award A1A0A1.
[3 marks]
Examiners report
This was one of the weakest questions on the paper. Many candidates failed to appreciate the significance of the absolute value and gave as the maximum value rather than . Another common error was to interpret the maximum value as greatest velocity or highest point rather than the point where the hill was steepest. A few candidates drew a graph that went from the starting point to the finishing point. What happened in between, often, showed little understanding of the relationship between the graphs of a function and its derivative. The section of the syllabus that mentions understanding derivatives through graphical methods needs more support from teachers.
This was one of the weakest questions on the paper. Many candidates failed to appreciate the significance of the absolute value and gave as the maximum value rather than . Another common error was to interpret the maximum value as greatest velocity or highest point rather than the point where the hill was steepest. A few candidates drew a graph that went from the starting point to the finishing point. What happened in between, often, showed little understanding of the relationship between the graphs of a function and its derivative. The section of the syllabus that mentions understanding derivatives through graphical methods needs more support from teachers.