The molarity of the stock solution is 1.25 M.
Step-by-step explanation:
We have to find the molarity of the stock solution using the law of volumetric analysis as, 
V1M1 = V2M2
V1 = 150 ml
M1 = 0.5 M
V2 = 60 ml
M2 = ?
 The above equation can be rearranged to get M2 as,
M2 = 

 Plugin the values as, 
 M2 = 

 = 1.25 M
So the molarity of the stock solution is 1.25 M.