O-LevelMathematicsStatistics4024/21 · May/June 2021 · Q29 Marks
A survey recorded the number of people living in each of 50 houses. The bar chart shows the results. [Figure 2.1]
- (a)Find the mode.[1]
- (b)Find the median.[1]
- (c)Calculate the mean.[3]
- (d)One of these houses is chosen at random. Find the probability that exactly 3 people live there.[1]
- (e)Two houses are chosen at random from these 50 houses. Find the probability that only one of the two houses has exactly 5 people living there.[3]
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] 4
- [1] 3
- [3] 3.22 or 3 11/50
- [3] B1 for 7, 11, 10, 12, 6, and 4 soi
- [3] M1 for (7×1+11×2+10×3+12×4+6×5+4×6)/50
- [1] 10/50 oe
- [3] 264/1225 oe
- [3] M2 for 6/50 × 44/49 [×2]
- [3] or M1 for a/50 × (50-a)/49 [×2] where 0 < a < 50
- [3] After 0 scored, SC1 for answer 528/2500
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