Question

A bag contains 5 red, 8 white and 7 black balls. A ball is drawn at random from the bag. Find the probability that the drawn ball is
i) red or white
ii) not a white ball​

Answer 1

Answer:

Total no. of balls in the bag is 20 (5 red, 7 black and 8 white)

Solution(i):

No. of red or white balls in bag is 13 (5 red and 8 white)

Therefore,

13

C

1

( Selecting 1 out of 13 items) times out of

20

C

1

( Selecting 1 out of 20 items) a red or white ball is picked.

Let E be the event of drawing a red or white ball from bag

We know that, Probability P(E) =

(Total no.of possible outcomes)

(No.of favorable outcomes)

=

20

C

1

13

C

1

=

20

13

Solution(ii):

No. of non-black balls in bag is 13 (5 red and 8 white)

Therefore,

13

C

1

( Selecting 1 out of 13 items) times out of

20

C

1

( Selecting 1 out of 20 items) a non-black ball is picked.

Let E be the event of drawing a non-black ball from bag

We know that, Probability P(E) =

(Total no.of possible outcomes)

(No.of favorable outcomes)

=

20

C

1

13

C

1

=

20

13

Solution(iii):

No. of neither black nor white balls in bag is 5 (5 red balls)

Therefore,

5

C

1

( Selecting 1 out of 5 items) times out of

20

C

1

( Selecting 1 out of 20 items) a neither white nor black ball is picked.

Let E be the event of drawing neither white nor black ball from bag

We know that, Probability P(E) =

(Total no.of possible outcomes)

(No.of favorable outcomes)

=

20

C

1

5

C

1

= 20/4

= 4/1