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got into the lift

by sanju09 » Sat Feb 20, 2010 5:16 am
Five personnel got into the lift compartment on the ground floor of an eight-storied house. If each of them can run off the compartment autonomously at any floor commencing from the first, what is the total number of ways in which all the five personnel can leave the compartment at dissimilar floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
Last edited by sanju09 on Sat Feb 20, 2010 5:21 am, edited 1 time in total.
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by shashank.ism » Sat Feb 20, 2010 5:19 am
sanju09 wrote:Five persons entered the lift cabin on the ground floor of an 8-floor house. If each of them can leave the cabin independently at any floor commencing from the first, what is the total number of ways in which all the five persons can leave the cabin at different floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
The number of such ways = 8P5 = 8x7x6x5x4 Ans B
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by harsh.champ » Sat Feb 20, 2010 5:20 am
sanju09 wrote:Five persons entered the lift cabin on the ground floor of an 8-floor house. If each of them can leave the cabin independently at any floor commencing from the first, what is the total number of ways in which all the five persons can leave the cabin at different floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
Since they can leave the floors independently,we have to consider all the 5 persons separately.
1st person can leave the lift cabin at any of the 8 floors.
Corresponding to it,2nd person an leave the lift cabin at any of the remaining 7 floors.

Similarly for the 3rd,4th and the 5th person.
Hence,the answer would be [spoiler](B) 8 × 7 × 6 × 5 × 4 [/spoiler]
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by sanju09 » Sat Feb 20, 2010 5:25 am
Really fast! Didn't give me time to change my wordings a bit. [spoiler]OA D[/spoiler]
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by shashank.ism » Sat Feb 20, 2010 5:31 am
sanju09 wrote:Really fast! Didn't give me time to change my wordings a bit. [spoiler]OA D[/spoiler]
ok then what is the new question. please change ur words..so that we can post ans according to the question sanju09
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by thephoenix » Sat Feb 20, 2010 8:35 am
sanju09 wrote:Five personnel got into the lift compartment on the ground floor of an eight-storied house. If each of them can run off the compartment autonomously at any floor commencing from the first, what is the total number of ways in which all the five personnel can leave the compartment at dissimilar floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
EIGHT STORIES IMPLIES THAT 7 MORE FLOOR ABOVE GROUND FLOOR
THERFORE THE FIRST ONE HAS 7 OPTION
SECOND ONE AS 6
.
.
.
.
LIKEWISE
7*6*5*4*3
D
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by shashank.ism » Sat Feb 20, 2010 8:43 am
thephoenix wrote:
sanju09 wrote:Five personnel got into the lift compartment on the ground floor of an eight-storied house. If each of them can run off the compartment autonomously at any floor commencing from the first, what is the total number of ways in which all the five personnel can leave the compartment at dissimilar floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
EIGHT STORIES IMPLIES THAT 7 MORE FLOOR ABOVE GROUND FLOOR
THERFORE THE FIRST ONE HAS 7 OPTION
SECOND ONE AS 6
.
.
.
.
LIKEWISE
7*6*5*4*3
D
ok I missed that point "each of them can run off the compartment autonomously at any floor commencing from the first"
so they can leave the lift from first floor...thats called bull's eye..good phoenix

I still have phoenix that does 8 storied building contains total 8 floor (including ground floor or excluding ground floor)
can any one help me out with this...??
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by harsh.champ » Sat Feb 20, 2010 8:49 am
sanju09 wrote:Five personnel got into the lift compartment on the ground floor of an eight-storied house. If each of them can run off the compartment autonomously at any floor commencing from the first, what is the total number of ways in which all the five personnel can leave the compartment at dissimilar floors?
(A) 7 × 7 × 6 × 6 × 5
(B) 8 × 7 × 6 × 5 × 4
(C) 7 × 7 × 6 × 5 × 4
(D) 7 × 6 × 5 × 4 × 3
(E) 6 × 6 × 5 × 4 × 3
Ok sanju09,in this case since you have written commencing from the first,the case of ground floor would not be considered.
Hence ,
1st person can leave the lift cabin at any of the 7 floors.(excluding the ground floor according to the edited question)
Corresponding to it,2nd person an leave the lift cabin at any of the remaining 6 floors.

Similarly for the 3rd,4th and the 5th person in 5,4 and 3 ways respectively.
So,the answer would be 7 x 6 x 5 x 4 x 3 i.e.D.
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