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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. 2/91
- B. 1/22
- C. 3/22
- D. 2/77
- Correct Answer
- 2/91
ExplanationLet S be the sample space.
Then, n(S) = number of ways of drawing 3 balls out of 15 = = = 455.
Let E = event of getting all the 3 red balls.
n(E) = = = 10.
=> P(E) = n(E)/n(S) = 10/455 = 2/91.
- 1.
x4 + y4 - 2x2 y2 isIf x = ?a + 1 , y = ?a - 1 , then the value of ?a ?a
Options- A. 16
- B. 20
- C. 10
- D. 5 Discuss
- 2. Express 0.82 68 as a vulgar fraction.
Options- A. 3093/4950
- B. 3043/4850
- C. 4093/4950
- D. 3039/4950 Discuss
- 3. What is the 11th term of the series 1, 8, 15, ...?
Options- A. 69
- B. 73
- C. 71
- D. 72 Discuss
- 4. The average age of 4 member of a family is 25 yr. If head of the family is included in this group then average age increase by 20%. Find out the age of the head.
Options- A. 45 yr
- B. 50 yr
- C. 55 yr
- D. 60 yr Discuss
- 5. A jar full of whisky contains 40 % of alcohol. A part of this whisky is replaced by another containing 19 % alcohol and now the percentage of alcohol was found to be 26. The quantity of whisky replaced is ?
Options- A. 2 5
- B. 1 3
- C. 2 3
- D. 3 5 Discuss
- 6. A can run 440 m in 51 seconds and B in 55 seconds. By how many seconds will B win if he has 40 m start?
Options- A. 1 seconds
- B. 2 seconds
- C. 3 seconds
- D. 4 seconds Discuss
- 7. 4/7 of a pole is in the mud. When 1/3 of it is pulled out, 250 cm of the pole is still in the mud. Find the full length of the pole .
Options- A. 1000
- B. 1100
- C. 950
- D. 1050 Discuss
- 8. The cost price of an article is 64% of the marked price. The gain percentage after allowing a discount of 12% on the marked price is
Options- A. 37 .5%
- B. 48%
- C. 50.5%
- D. 52% Discuss
- 9. If a3 ? b3 = 56 and a ? b = 2, then the value of ( a2 + b2 ) is :
Options- A. ? 10
- B. ? 12
- C. 20
- D. 18 Discuss
- 10. An anti-aircraft gun can take a maximum of four shots at an enemy plane moving away from it ,The probability of hitting the plane at the first, second, third and fourth shots are 0.4, 0.3, 0.2, and 0.1 respectively. What is the probability that the plane is hit when all the four shots are fired?
Options- A. 0.4379
- B. 0.6872
- C. 0.6976
- D. 0.3507 Discuss
More questions
Correct Answer: 16
Explanation:
Correct Answer: 4093/4950
Explanation:
0.8268 = (8268 - 82)/9900
= 8186/9900
= 4093/4950
Correct Answer: 71
Explanation:
This is an AP with a = 1 and d = 7
? 11th term = a + (n - 1) x d = 1 + (11 - 1) x 7
= 1 + 10 x 7 = 71
Correct Answer: 50 yr
Explanation:
Total age of 4 member = 25 x 4 = 100 yr
Total age of 5 members including the head
= 5 x (25 + 25 x 20/100)
= 5 x 30 = 150 yr
? Age of the head = 150 - 100 = 50 yr
Correct Answer: 2 3
Explanation:
Correct Answer: 1 seconds
Explanation:
To reach the winning post B will have to cover the distance (440 ? 40) = 400 m.
Hence,
time taken by B to cover 440 meter = 55
time taken by B to cover 1 meter = 55 / 440
time taken by B to cover 400 meter = 400 x 55 / 440 = 40 x 55/44 =10 x 55/11 = 10 x 5
time taken by B to cover 400 meter = 50 Sec.
Since, A reaches the winning post in 51 sec. while B in 50 sec.
So, B will win by 1 second.
Correct Answer: 1050
Explanation:
Let us assume length of pole is L.
Length of the pole in Mud is = L x 4/7 = 4L/7
Length of the Pole which is pulled out = L x 1/3 = L/3
Length of the pole is still in mud = Length of the pole in Mud - Length of the Pole which is pulled out
Length of the pole is still in mud = 4L/7 - L/3
According to question,
Length of the pole is still in mud = 250
4L/7 - L/3 = 250
(4L x 3 - L x 7)/7 x 3 = 250
12L - 7L = 250 x 21
5L = 250 x 21
L = 250 x 21/5
L = 50 x 21
L = 1050
Correct Answer: 37 .5%
Explanation:
Let MP of the article = ? N
? C P of the article = (N x 64) / 100 = ? 16N/25
And SP of the article = [N x (100 - 12)]/100 = ? (N x 22)/25
? profit = [ 22N/25 - 16N/25 ] = ? 6N/25
Hence, profit per cent = [(6N/25) / (16N/25)] x 100%
= (6 x 100)/16 = 37.5%
Correct Answer: 20
Explanation:
As we know from the algebra formula,
(a ? b)3 = a3 ? b 3 ? 3ab (a ? b) .......................(1)
As per given question,
a3 ? b 3 = 56 and a ? b = 2
Put these value in above equation (1) . We will get,
? 23 = 56 ? 3ab x 2
? 8 = 56 ? 3ab x 2
? 8 = 56 ? 6ab
? 6ab = 56 ? 8 = 48
? ab = 8 ...................... (i)
? a2 + b2 = (a ? b)2 + 2ab
? a2 + b2 = (a ? b)2 + 2ab
Put the value of
? a2 + b2 = 22 + 2 x 8
? a2 + b2 = 4 + 16 = 20
Correct Answer: 0.6976
Explanation:
First we find the probability that the plane is not hit
= (1 - 0.4) ( 1 - 0.3) (1 - 0.2) (1 - 0.1)
= 0.6 x 0.7 x 0.8 x 0.9 = 0.3024
? probability that the plane is hit = 1 - 0.3024
= 0.6976
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