What is the relative frequency of plastic buttons with four holes? round to the nearest hundredth, if needed.
0.11 0.35 0.66 0.90

Relative frequency of plastic buttons with four holes is 28/80 = 0.35

Relative frequency of plastic buttons with two holes is 15/80 = 0.1875
Relative frequency of wooden buttons with two holes is 34/80 = 0.425
Relative frequency of wooden buttons with four holes is 3/80 = 0.0375

0.35 + 0.1875 + 0.425 + 0.0375 = 1