In a box containing 100 bulbs, 10 are defective The probability that out of a
sample of 5 bulbs, none is defective is
(A) 10–1
(B)
⎛215
⎞
⎜
⎟
⎝
⎠
(C)
⎛1095
⎞
⎜
⎟
⎝
⎠
(D)
9
10
15 The probability that a student is not a swimmer is 1 5  Then the probability that
out of five students, four are swimmers is
(A)
4
5
4
4
1
C
5
5
⎛
⎞
⎜
⎟
⎝
⎠
(B)
44
1
5
5
⎛
⎞
⎜
⎟
⎝
⎠
(C)
4
5
1
1
4
C 5
⎛5
⎞
⎜
⎟
⎝
⎠
(D) None of these
Miscellaneous Examples
Example 33 Coloured balls are distributed in four boxes as shown in the following
table:
Box
Colour
    Black      White       Red
 Blue
I
3
4
5
6
II
2
2
2
2
III
1
2
3
1
IV
4
3
1
5
A box is selected at random and then a ball is randomly drawn from the selected
box