please let me know what book you found a similar answer or steps on how to solve this one.
there are many books for that kind of problems first you refer book of aruldas and book name is 1000 solve problems on quantum mechanics
and i suggest you to refer introduction to quantum mechanics by d.j . Griffith.
and also you see solutions manual of Thus book
so first try yourself and then look at in solution manual.
.
please let me know what book you found a similar answer or steps on how to...