Final answer:
The questions are related to extracting specific data from given relations, typical of SQL database queries. This involves identifying PC models by speed, manufacturers by product attributes, and printer models by color and type. Example concepts given include pricing standard deviation and computer memory card specifications.
Step-by-step explanation:
The questions provided are characteristic of database queries within the realm of relational databases. Addressing these questions would typically require using SQL or similar query languages to extract data from the given relations. When examining the The practical examples provided involve price analysis and computer components, looking at concepts such as standard deviation in pricing, memory card data transfer rates, and byte measurement prefixes. For example, the unit for one million bytes is a megabyte (MB).(a)
To find the PC models with a speed of at least 1000, we need to use the PC relation. We can filter out the PC models that have a speed of at least 1000 by querying the PC relation with the condition 'speed >= 1000'. The result will be the list of PC models that meet this criteria.(b) To identify the manufacturers that make laptops with a hard disk of at least one giga-byte, we need to use the Product and PC relations. First, we can filter out the laptops in the Product relation by querying 'type = laptop'. Then, we can join the filtered laptops with the PC relation using the 'model' attribute. Finally, we can filter out the laptops with a hard disk of at least one giga-byte by querying 'hd >= 1000'. The result will be the list of manufacturers that make these laptops.