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- Question
A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?
Options- A.
10 21 - B.
11 21 - C.
2 7 - D.
5 7 - Correct Answer
-
10 21
ExplanationTotal number of balls = (2 + 3 + 2) = 7.Let S be the sample space.
Then, n(S) = Number of ways of drawing 2 balls out of 7 = 7C2 ` = (7 x 6) (2 x 1) = 21. Let E = Event of drawing 2 balls, none of which is blue.
∴ n(E) = Number of ways of drawing 2 balls out of (2 + 3) balls. = 5C2 = (5 x 4) (2 x 1) = 10. ∴ P(E) = n(E) = 10 . n(S) 21
More questions
- 1. The median for the data 2, 4, 6, 8, 10, 12, 14 is
Options- A. 6
- B. 8
- C. 9.5
- D. 10 Discuss
Correct Answer: 8
Explanation:
4th observation i.e., 8 is the median.
- 2. The value of 47 / 10000 is?
Options- A. .0047
- B. .0470
- C. .00047
- D. .000047 Discuss
Correct Answer: .0047
Explanation:
47/10000 = .0047
- 3. If 4x = 18y, then the value of ( x/y - 1) is
Options- A. 1 3
- B. 7 2
- C. 2 3
- D. 3 2 Discuss
Correct Answer: 7 2
- 4. If the price of 23 toys is Rs. 276, then what will the price (Rs.) of 12 toys?
Options- A. 144
- B. 158
- C. 159
- D. 166 Discuss
Correct Answer: 144
Explanation:
- 5. .02 =(......?.....)%
Options- A. 20
- B. 2
- C. .02
- D. .2 Discuss
Correct Answer: 2
Explanation:
.02 =(2/100) x 100% =2%
- 6. If 36 men can do a piece of work in 25 hours, in how many hours will 15 men do it?
Options- A. 45
- B. 55
- C. 60
- D. 72 Discuss
Correct Answer: 60
Explanation:
- 7. 2?63 / 11 =233
Options- A. 4
- B. 3
- C. 6
- D. 5 Discuss
Correct Answer: 5
Explanation:
Let N / 11 = 233
Then, N = 233 x 11 = 2563
? Missing digit is 5.- 8. When 121012 is divided by 12, the remainder is
Options- A. 0
- B. 2
- C. 3
- D. 4 Discuss
Correct Answer: 4
Explanation:
121012 = 12 x 10084 + 4
? remainder = 4- 9. 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 Discuss
Correct Answer: 18 days
Explanation:
We have the important relation, More work, More time (days)
? A piece of work can be done in 6 days.
? Three times of work of same type can be done in 6 x 3
= 18 days- 10. 750.0003 ÷ 19.999 =?
Options- A. 49
- B. 18
- C. 22
- D. 38 Discuss
Correct Answer: 38
Explanation:
? = 750.0003 ÷ 19.999
? ? ? 750 ÷ 20
? ? ? 375 ? 38
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