A-LevelMathematicsProbability and statistics9709/61 · May/June 2017 · Q46 Marks
The times taken, t seconds, by 1140 people to solve a puzzle are summarised in the table. Time (t seconds): 0 < t < 20, 20 < t < 40, 40 < t < 60, 60 < t < 100, 100 < t < 140 Number of people: 320, 280, 220, 220, 100
- (i)On the grid, draw a histogram to illustrate this information.[4]
- (ii)Calculate an estimate of the mean of t.[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 2017). The mark or mark type is shown in brackets.
- [M1] Attempt at fd (must be at least 3 freq/cw) – may be implied by graph
- [A1] Correct heights seen on graph i.e. must see a gap for fd = 2.5 etc.
- [B1] Correct end points of bars and correct widths
- [B1] labels fd, sec. Time can be optional. Linear axes, condone 0 < t < 20 etc.
- [M1] using Σ fx / n with mid-point attempt ±0.5, not ends not class widths
- [A1]
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