A. 1/20
B. 3/10
C. 1/5
D. 4/5
Explanation:
Six persons can be arranged in a row in 6! ways. Treat the three persons to sit together as one unit then there four persons and they can be arranged in 4! ways. Again three persons can be arranged among them selves in 3! ways. Favourable outcomes = 3!4! Required probability = 3!4!/6! = 1/5
Related Mcqs:
- The average age of seven persons sitting in a row facing east is 28 years. If the average age of the first three persons is 21 years and the average age of the last three persons is 34 years, then find the age of the person sitting in the middle of the row?
A. 30 Years
B. 31 years
C. 26 years
D. 33 years - In how many ways can live boys and three girls sit in a row such that all boys sit together?
A. 4800
B. 5760
C. 2880
D. 15000 - The number of ways in which six boys and six girls can be seated in a row for a photograph so that no two girls sit together is_________?
A. (6!)2
B. 6! * ⁷P₆
C. 2(6!)
D. 6! * 7 - A gardener was asked a plant flowers in a row containing equal number of plants. He tried to plant 6, 8, 10 and 12 in each row, but 5 plants left in each case. When he planted 13 in a row, no plant was left. Find the number of plants with him?
A. 245
B. 125
C. 485
D. 845 - A man can row 9 1/3 km/hr in still water and he finds that is thrice as much time to row u p than as to row down the same distance in river. The speed of the current is:________?
A. 3 1/3 km/hr
B. 3 1/9 km/hr
C. 1 ¼ km/hr
D. 4 2/3 km/hr - The average weight of 25 persons sitting in a boat had some value. A new person added to them whose weight was 46 kg only. Due to his arrival, the average weight of all the persons decreased by 5 kg. Find the average weight of first 25 persons?
A. 55 kg
B. 62 kg
C. 56 kg
D. None - A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. How far is the place?
A. 3.12 km
B. 2.88 km
C. 3 km
D. 2 km - A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?
A. 6.24 km
B. 6 km
C. 5.76 km
D. 5.66 km - A man can row a boat at 20 kmph in still water. If the speed of the stream is 6 kmph, what is the time taken to row a distance of 60 km downstream?
A. 20/6 hours
B. 27/2 hours
C. 30 hours
D. 30/13 hours - A man rows at a speed of 6 km/hr in still water. If the time taken to row a certain distance upstream is 4 times the time taken to row the same distance downstream, what is the speed of the river?
A. 1.8 km/hr
B. 3 km/hr
C. 3.6 km/hr
D. 4 km/hr
