Question

The lab has decided to allow variations of the original sequence so that input of the scanned sequence of five fingers is allowed to vary from the original sequence by one place for any of the fingers. Thus, for example, if TIMRL is the original sequence, then ITRML is also allowed, but LIMIT is not.
How many different sequences are allowed for any given person's original scan?

• A. 7
• B. 5
• C. 8
• D. 13

Answer 1

The correct option is C 8

Let the original sequence be T I M R L.
T can interchange its place with only I, so the number of ways = 1
I can interchange its place with T and M, so the number of ways = 2
M can interchange its place with I and R, so the number of ways = 2
R can interchange its place with M and L, so the number of ways = 2
L can interchange its place with R only, so the number of ways = 1
Therefore, total number of different sequence possible = $1\times 2\times 2\times 2\times 1=8$.