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- Question
fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ?
Options- A. 3/91
- B. 2/73
- C. 1/91
- D. 3/73
- Correct Answer
- 3/91
ExplanationIn a circle of n different persons, the total number of arrangements possible = (n - 1)!
Total number of arrangements = n(S) = (15 ? 1)! = 14 !
Taking three persons as a unit, total persons = 13 (in 4 units)
Therefore no. of ways for these 13 persons to around the circular table = (13 - 1)! = 12!
In any given unit, 3 particular person can sit in 3!. Hence total number of ways that any three person can sit =
n(E) = 12! X 3!
Therefore P (E) = probability of three persons sitting together = n(E) / n(S) = 12! X 3 ! / 14!
= 12!x3x2 / 14x13x12! = 6/14x13 = 3/91 - 1. 10 men can make a wall in 8 days. How many men required to complete the same work in half days?
Options- A. 80
- B. 100
- C. 120
- D. 160 Discuss
- 2. A and B separately can complete a work in 6 days and 3 days respectively. If they work together, then in how many days will they complete the work?
Options- A. 4 days
- B. 3 days
- C. 2 days
- D. 5 days Discuss
- 3. (5568 ÷ 87) 1/3 + (72 x 2) 1/2 = (?) 1/2
Options- A. 256
- B. 4
- C. ?2
- D. 16 Discuss
- 4. ( .803 x .647 + .803 x .353 ) =?
Options- A. .803
- B. 1
- C. .45
- D. 1.450 Discuss
- 5. If 6 years are subtracted from the present age of Randheer and the remainder is divided by 18 than the present age of his grandson Anup is obtained. If Anup is 2 years younger to mahesh whose age 5 years, then what's the age of Randheer?
Options- A. 96 years
- B. 84 years
- C. 48 years
- D. 60 years Discuss
- 6. In a family, the average age of father and mother is 35 yr. The average age of the father, mother and their only son is 27 yr. What is the age of the son?
Options- A. 12 yr
- B. 11 yr
- C. 10.5 yr
- D. 10 yr Discuss
- 7. 15, 31, 63, 127, 255, (....)
Options- A. 513
- B. 511
- C. 517
- D. 523 Discuss
- 8. 356 x 936 - 356 x 836 =?
Options- A. 35600
- B. 34500
- C. 49630
- D. 93600 Discuss
- 9. In a right angled ? ABC, Right angled at A, AD ? BC. Then :
Options- A. AD2 = BD × CD
- B. AD2 = AB × AC
- C. AD2 = BD × AB
- D. AD2 = CD × AC Discuss
- 10. By how much is 30% of 80 greater than 4/5 th of 25?
Options- A. 2
- B. 4
- C. 10
- D. 15 Discuss
More questions
Correct Answer: 160
Explanation:
Given M1 = 10
D1 = 8, M2= ? and D2 = 1/2
From M1 D1 = M2 D2
? 10 x 8 = M2 x 1/2
? M2= 10 x 8 x 2
? M2 = 160
Correct Answer: 2 days
Explanation:
Work completed by A + B in one day = 1/6 + 1/3 = 1/2
? Time taken by A + B to complete the work = 2 days.
Correct Answer: 256
Explanation:
(?)1/2 = (5568 ÷ 87)1/3 + (72 x 2)1/2
= (64)1/3 + (144)1/2
? ? = (4 + 12)2 = 256
Correct Answer: .45
Explanation:
Given Expression = ( .803 x .647 + .803 x .353 )
= 803 x (.647 + .353)
= .803 x 1
= .803
Correct Answer: 60 years
Explanation:
? Anup's age = (5 - 2) years = 3 years
Let Randheer's age be x years.
Then, (x - 6)/18 = 3
? x = 54 + 6 = 60
Correct Answer: 11 yr
Explanation:
? Total age of father and mother = 35 x 2 = 70 yr
and total age of father, mother and son = 27 x 3 = 81 yr
&there4: Age of son = 81 -70 = 11 yr
Correct Answer: 511
Explanation:
So, the next number is (255 x 2) + 1 = 511.
Correct Answer: 35600
Explanation:
356 x 936 - 356 x 836 = 356 x (936 - 836 )
= 356 x 100
= 35600.
Correct Answer: AD2 = BD × CD
Explanation:
Correct Answer: 4
Explanation:
It is (30 x 80)/100 - (4 x 25)/ 5 = 24 - 20 = 4
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