zelda
Member
could someone explain question 16 (digital signal question) and question 19??
i dont get it ><
thanks
i dont get it ><
thanks
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2003 MC q's (1 Viewer)
- Thread starter zelda
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Q16 - at 2 seconds, the height is 2 which in binary 2 stands for 010 (remembering that binary can only be written in 0s and 1s and order is 1,2,4,8...so on - the powers of 2 - going from right to left), so there are no 1s, 1x 2 and 0x4. At 3 seconds the height is 4 so is written as 100 (binary for 4) and at 4 seconds the height is 1 which in binary is 001.
Q19 - The primary keys for the Student and Subject tables are Stu_ID and Subj_ID respectively, and if you look at the Enrol table both those keys are located there, but logically none of them would be primary keys. Since they are the primary keys of the Student and Subject tables they are therefore foreign keys (def. attribute(field) of a table that is a primary key of another table)
Hope that helps!
Q19 - The primary keys for the Student and Subject tables are Stu_ID and Subj_ID respectively, and if you look at the Enrol table both those keys are located there, but logically none of them would be primary keys. Since they are the primary keys of the Student and Subject tables they are therefore foreign keys (def. attribute(field) of a table that is a primary key of another table)
Hope that helps!