A-LevelMathematicsProbability and statistics9709/53 · May/June 2021 · Q15 Marks

The heights in cm of 160 sunflower plants were measured. The results are summarised on the following cumulative frequency curve. [Figure 1.1: Cumulative frequency curve showing heights of sunflower plants]

(a)Use the graph to estimate the number of plants with heights less than 100 cm.[1]
(b)Use the graph to estimate the 65th percentile of the distribution.[2]
(c)Use the graph to estimate the interquartile range of the heights of these plants.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[1] B1 Accept 60 or 61. No decimals
[2] M1 0.65 × 160 (=104) seen unsimplified or implied by use on graph
A1 Use of graph must be seen. SCB1 correct value (136 only) if neither 104 nor use of graph are evident
[2] M1 UQ-LQ ; 148 < UQ < 152; 74 < LQ < 78.
A1 Must be from 150 - 76

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.

Topic: Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 5 marks.
Source: A-Level Mathematics, May/June 2021 Paper 5 Variant 3, question 1.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content