A typical project manager will get a range, take the lower bound and communicate it as the only relevant number to every other stakeholder. When that inevitably does not work out, all the blame will be passed on to you unfiltered.
Depending on where you work it may or may not be worth giving someone new the benefit of the doubt, but in general it is safer to only ever talk about the upper bound and add some padding.
RustyRooster: C is the root of all modern languages
FORTRAN: Am I a joke to you?