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Practice By Tag: COMP 2804 Midterm

Question: 2019 Fall Midterm - 5
1 . Consider strings of length 4 over the alphabet $\{a,b,c,d\}$. How many such strings are there that start with $ad$ or end with $dcb$?
(a)
20
(b)
17
(c)
19
(d)
18