8. Petra has 49 blue beads and one red bead. How many beads must Petra remove so that $90 \%$ of her beads are blue?
A 4
B 10
C 29
D 39
E 40
8. E For the one red bead to be $10 \%$ of the final number of beads, there must be nine blue beads representing $90 \%$ of the final number of beads. Therefore the number of beads Petra must remove is $49-9=40$.