Question Numbers : (63 to 66) : A high security
research lab requires the researchers to set a pass key
sequence Passed on the scan of the five fingers of their
left hands. When an employee first joins the lab, her
fingers are scanned in an order of her choice, and then
when she wants to re-enter the facility, she has to scan
the five fingers in the same sequence.
The lab authorities are considering some relaxations of
the scan order requirements, since it is observed that
some employees often get locked-out because they
forget the sequence.
The lab has decided to allow a variation in the
sequence of scans of the five fingers so that at most
two scans (out of five) are out of place. For example,
if the original sequence is Thumb (T), index finger
(I), middle finger (M), ring finger (R) and little finger
(L) then TLMRI is also allowed, but TMRLI is not.
How many different sequences of scans are allowed
for any given person’s original scan?