A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random

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Question
A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:
Options
A.

1

22
B.

3

22
C.

2

91
D.

2

77

Correct Answer

2

91

Explanation

Let S be the sample space.

Then, n(S)

= number of ways of drawing 3 balls out of 15

= ¹⁵C₃

=	(15 x 14 x 13)
	(3 x 2 x 1)

= 455.

Let E = event of getting all the 3 red balls.

∴ n(E) = ⁵C₃ = ⁵C₂ =	(5 x 4)	= 10.
	(2 x 1)

∴ P(E) =	n(E)	=	10	=	2	.
	n(S)		455		91

More questions

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Aarti can do a piece of work in 6 days. In how many days will she complete three time of work of same type?
Options
A. 18 days
B. 21 days
C. 3 days
D. 6 days

4.
Let A = {1, 2, {3, 4}, 5}. Which of the following statements is true?
Options
A. {3, 4} ? A
B. {3, 4} ? A
C. 1 ? A
D. {1, 2, 5} ? A

5.
Two vessels A and B contains milk and water mixed in the ratio 5 : 3 and 2 : 3. When these mixtures are mixed to form a new mixture containing half milk and half water, they must be taken in the ratio ?
Options
A. 2 : 5
B. 3 : 5
C. 4 : 5
D. 7 : 3

7.
A tree is 12 m tall and casts an an 8 m long shadow. At the same time, a flag pole caste a 100 m long shadow. How long is the flag pole?
Options
A. 150 m
B. 200 m
C. 125 m
D. 115 m

9. A certain amount earns simple interest of Rs. 1750 after 7 years. Had the interest been 2% more, how much more interest would it have earned?
Options
A. Rs. 35
B. Rs. 245
C. Rs. 350
D. Cannot be determined
E. None of these

10.
If the hands of a clock coincide in every 65 minutes (true time), in 24 hours the clock will gain:
Options
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