Hi, if there are any horn players here, is it possible to remove the mute (straight mute) within 3 crotchet rests and then play, or is more time needed?
Also, is a marimba part of a standard orchestral percussion section, or is it out of the norm so to speak??

Thanks

Amateur orchestra: definitely not. An orchestra might be lucky and have a regular percussion player who owned one, but they are seriously expensive (e.g. 1200 US dollars for a 3-octave one with synthetic bars - the best have rosewood!), so it's probably not common.

Professional orchestra: I doubt it. Again, an individual player might own one, but I think it's likely that most orchestras would hire one as needed. A high proportion of standard orchestral repertoire doesn't need it. Recent repertoire is likely to need the biggest - 5 octaves.