Question Number 104708 by byaw last updated on 23/Jul/20

   A bag contains 12 white balls   and 8 black balls, another   contains 10 white balls and 15  black balls. If two balls are drawn  wthout replacement from each  bag, find the probability that:     i. all the four balls are black     ii. exactly one of the four balls is  white

Answered by som(math1967) last updated on 23/Jul/20

i) All 4 balls are black  (c_2 ^8 /c_2 ^(20) )×(c_2 ^(15) /c_2 ^(25) )=((28)/(190))×((105)/(300))=((28)/(950))  ii)(c_2 ^8 /c_2 ^(20) )×((c_1 ^(15) ×c_1 ^(10) )/c_2 ^(25) ) +((c_1 ^8 ×c_1 ^(12) )/c_2 ^(20) )×(c_2 ^(15) /c_2 ^(25) )

Commented bybyaw last updated on 23/Jul/20

please help with the question  below     A box contains 5 white 3 black  balls and 2 red balls of the same  size. A ball is selected at random  from the box and then replaced. A  second ball is then selected. Find  the probability of obtaining one  black ball or red ball

Commented bysom(math1967) last updated on 24/Jul/20

(WB)or(BW)or(BR)or(RB)  (RW)or(WR)  (5/(10))×(3/(10)) ×2+(3/(10))×(2/(10))×2+(2/(10))×(5/(10))×2  2×(((31)/(100)))=((31)/(50))

Commented by1549442205PVT last updated on 24/Jul/20

this solution is for the question:  Find the probality so that  two balls drawn   different colour sir?Sir looking back once again   the question of problem!

Commented bysom(math1967) last updated on 24/Jul/20

If one black ball obtain then  red ball not obtain then  solution is   2×((5/(10))×(3/(10)) +(5/(10))×(2/(10)))  2×(1/4)=(1/2)

Commented bybyaw last updated on 24/Jul/20

Thank you very much