Fig. 1 is a sketch map used in a fieldwork enquiry into congestion near a new market in Ibadan, Nigeria. Six students stood at three road locations marked A...
Question 1 Report
Fig. 1 is a sketch map used in a fieldwork enquiry into congestion near a new market in Ibadan, Nigeria. Six students stood at three road locations marked A, B and C. They recorded every vehicle passing their position between 07:45 and 08:00 on a Tuesday. Table 1 gives the data after the groups combined their tally sheets. The study also noted that location B is beside the market entrance, while location C is 350 metres from it.
Table 1 Vehicle observations during the 15-minute count
| Location | Cars | Minibuses | Motorcycles | Total vehicles |
|---|---|---|---|---|
| A | 84 | 19 | 46 | 149 |
| B | 126 | 31 | 72 | 229 |
| C | 63 | 12 | 39 | 114 |
(a) State the location with the greatest total number of vehicles. [1]
(b) Calculate the mean number of cars recorded per minute at location B. Give your answer to one decimal place. [2]
(c) Describe two differences between the traffic data at locations B and C. [3]
(d) Suggest two improvements to the method that would make this fieldwork enquiry more reliable. [2]
(e) Explain one reason why the data from this single Tuesday morning may not represent usual traffic conditions in the study area. [2]
Answer Details
- (a) Location B has the greatest total vehicle count: 229 vehicles. [1]
- (b) The count lasted 15 minutes and 126 cars were recorded at location B.
\[\frac{126\text{ cars}}{15\text{ minutes}}=8.4\text{ cars per minute}\]
The mean is 8.4 cars per minute. [2] - (c) Location B had more traffic than location C in each category. It recorded 229 total vehicles compared with 114 at C. It also recorded 126 cars compared with 63, 31 minibuses compared with 12, and 72 motorcycles compared with 39. Any three accurate comparative statements gain credit. [3]
- (d) Reliability could be improved by repeating the counts on several days and calculating a mean. Counts could also be made at different times of day, including midday or evening, or several observers could compare their tally sheets while using the same synchronised timed interval. Any two valid improvements gain credit. [2]
- (e) One Tuesday morning may be unusual because traffic varies between days. For example, market deliveries or school attendance may differ. In addition, rain, a crash, roadworks, a public event or a road closure could alter the vehicle flow. These temporary conditions mean the data may not represent usual traffic. [2]
Examination reminder: for a reliability improvement, state both what is repeated or controlled and how this makes the evidence more dependable.
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