A meter bridge also called a slide wire bridge is an instrument that works on the principle of a Wheatstone bridge. A meter bridge is used in finding the unknown resistance of a conductor as that of in a Wheatstone bridge.
Solution
R:S=3:2
S=10Ω
Ratio,
R/S = 3/ 2
R=3/2 x 10Ω = 5
The length of 1Ω wire as per the given condition
l=1.5 / 1.5
l=1/10
= 0.1 m
= 1.0 x 10-1m
Answer
The length of the wire is 1.0 x 10-1m
Check out the video below to know more about the factors that affect resistance

Further Reading