Step-by-step explanation:
When Michelson-Morley apparatus is turned through
then position of two mirrors will be changed. The resultant path difference will be as follows.

Formula for change in fringe shift is as follows.
n =


v =

According to the given data change in fringe is n = 1. The data is Michelson and Morley experiment is as follows.
l = 11 m
c =
m/s
Hence, putting the given values into the above formula as follows.
v =

=

=

Thus, we can conclude that velocity deduced is
.