MIT1_204S10_quiz01_2008_so

# MIT1_204S10_quiz01_2008_so - 1.204 Quiz 1 Solutions Spring...

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1.204 Quiz 1 Solutions Spring 2008 Name ______________________________________________________ Exam guidelines: 1) 80 minutes are allowed to complete the quiz. 2) Open notes; open book. 3) There are 4 questions (100 points) and 7 pages (including this one) in the exam booklet. 4) No laptop computers, calculators, cell phones or messaging devices are allowed. Please turn off any that you have brought. 5) Please write legibly you are welcome to use both sides of the paper; we can provide additional paper if necessary.

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Question 1. Data modeling (25 points) There is a set of traffic sensors that count cars in an urban area. Some are at the approaches to intersections, one sensor per lane of traffic entering the intersection. Other sensors are between intersections, one sensor per lane of traffic on the road. An intersection has several lanes entering it. Each lane is associated with a road. Each sensor has a status (working or not) and a count of the number of vehicles it has detected, in 5 second intervals, for the previous 3 minutes. Each road and each intersection has a name and a unique identifier. Draw a data model that corresponds to this set of system rules. You only need to create one drawing that includes all the elements listed in steps a-e. a. Draw a box for each entity: give each an appropriate name b. List the attributes in the box for each entity c. Indicate the primary key for each entity by placing the phrase (PK) next to its name. d. Draw all relationships between the entities in the model. Indicate foreign keys by placing the phrase (FK) next to attributes that are foreign keys.
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MIT1_204S10_quiz01_2008_so - 1.204 Quiz 1 Solutions Spring...

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