Ethan recorded the grade-level and instrument of everyone in the middle school School of Rock below.
Seventh Grade Students
Instrument # of Students
Guitar 10
Bass 4
Drums 14
Keyboard 14
Eighth Grade Students
Instrument # of Students
Guitar 6
Bass 6
Drums 15
Keyboard 10

Based on these results, express the probability that a seventh grader chosen at random will play an instrument other than bass as a percent to the nearest whole number.