The table below describes band members at Mike's school.
Band Member Knowledge of Instruments
Can Play
More than One Instrument
Can Only Play
One
Instrument
15
Grade 6
Grade 7
Grade 8
20
6
8
7
18
Mike used the computation
-0.33 = 33% to find the percentage of eighth-grade band members who can play more
than one instrument What error did Mike make?