A bag contains six white beads and four black beads. You pick out a bead at random, record it's color and put the bead back in the bag. You repeat this process 35 times. How many times would you expect to remove a white bead from the bag?

You have a total of 10 beads in the bag. Since each time you pick out a bead, you put it back ... the number of beads to choose from remains constant at 10. Since 6 of those beads are white, you have a 6/10 chance of pulling a white bead each time.

6/10 = 60/100 = 60%

Now multiply 60% times the number of attempts.

Change 60% to decimal by dividing by 100 (move decimal 2 places left).

.60 * 35 = 21

I would expect to draw a white bead 21 out of 35 attempts.

Probability of white is 6/10, since the bead is put back each time the chance of it being white is 6/10.