May have/might have

Nobody is answering the door.

1) -They may have gone out.

2) -They might have gone out.

Which is correct in this context?

3) Pete may have given you a ride if he had driven here instead of taking a cab.

4) Pete might have given you a ride if he had driven here instead of taking a cab

Which is correct? '3' or '4'?

Gratefully,

Navi.