1 It happens every season - by sheer chance and law of averages some of the ideas are bound to come up.

2 I only discovered I was in it by sheer chance.

3 I met her by sheer chance.

4 Other than by sheer chance, Voldemort might have thought Neville was " the Chosen One."

5 As always, we needed good information, and sometimes this came our way by sheer chance.