A bag contains only 8 beads
The beads are identical in all respects except colour.
3 of the beads are black and the other 5 beads are white.
A bead is taken at random from the bag and not replaced.
A second bead is then taken at random from the bag.
What is the probability that both beads are black?
i tried 3/8 + 2/7
hi
i did 3/8 * 2/7 = 3/28
what is the correct solution?
yes that is correct, but why multiply instead of add like i did, can you explain why?
because we use the probability equations
let’s say P(A)=picking a black bead during the first draw
P(B)=picking a black bead during the second draw
P(both)=P(A) * P(B/A)
in other words = P(A) * P(B knowing we picked a black bead during the first draw)
thank you so much juliette