First of all, we need to know the conversion from hours to seconds. We know that there are 60 min./hr. and 60 sec./min. Multiplying gives the appropriate conversion:
(60 sec./min.)*(60 min./hr.) = 3600 sec./hr.
We can now proceed with the problem. We are given that the bottle capping rate is 3 bottles/sec. So multiply:
(3 bottles/sec.)*(3600 sec./hr.)*(15 hr.) = 162000 bottles.