October 2020 Paper 2 Q4

OCR MEICurrent spec2 marksData Processing

4 Fig. 4 shows a cumulative frequency diagram for the time spent revising mathematics by year 11 students at a certain school during a week in the summer term.

Fig. 4: cumulative frequency curve for Year 11 students through (0, 0), (20, 85), (40, 125), (60, 158), (80, 183), (100, 189), (120, 197); time in minutes from 0 to 140 — Fig. 4

(a) Use the diagram to estimate the median time spent revising mathematics by these students. [1]

A teacher comments that 90% of the students spent less than an hour revising mathematics during this week.

(b) Determine whether the information in the diagram supports this comment. [1]

Scheme	Marks	AO
\(23 \leqslant m \leqslant 29\)	B1	1.1
	[1]

Mark scheme (b)

Scheme	Marks	AO
no, \(p\)% spent less than an hour revising maths; or no, 90% spent less than m minutes revising maths	B1	2.4
	[1]

Notes

B1: \(75 \leqslant p \leqslant 85\)
\(75 \leqslant m \leqslant 100\)
Allow eg \(x\) out of 200 is not 90% or 0.9 oe where \(150 \leqslant x \leqslant 170\)