There is a 4 storied building. In every floor 4 sets are available so total 16 room sets are availab

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20 Jan 2012 building

There is a 4 storied building. In every floor 4 sets are available so total 16 room sets are available. I have to knock 3 out of these 16 for finding the room of my friend. What will be the probability to get the friends room?

OPtion

1) 13*14*15/16*16*16
2) 1/16*16*16
3) 15/16
4) 1/16
5) 1/8
6) 3/16
7) 13/16
8) 7/8
9) 1/2
10) none of these

Solution

probability of failure = (15/16)(14/15)(13/14) = 13/16
so probability of success = 1 - 13/16 = 3/16

Correct Option: 6 Best Solution (4)

Rakesh Kumar Kohli   12 years AGO

Probability to get the friends roomduring first knock = 1/16
Probability to get the friends room during second knock = (15/16)*(1/15) = 1/16
Probability to get the friends room during third knock = (15/16)*(14/15)*(1/14) = 1/16
Thus Probability to get the friends room = 1/16+1/16+1/16 = 3/16

Like? Yes (5) | No   

Rupayan Mondal   12 years AGO

probability = no of chance/total no of sample space...
Hence P = 3/16

Like? Yes (4) | No   

rahul kumar dhamu   12 years AGO

probability of roam in particular floor=1/4
probability that in 3 knock we find right door=3/4
so required probability is 3/4 * 1/4 =3/16

Like? Yes (2) | No (1)  

Anish Philip   12 years AGO

probability of not finding the room = 15/16*14/15*13/14
probability of finding the room = 1 - not finding
= 0.1875

Like? Yes (1) | No (1)