*here is a problem on a ar* in a big hostel,there r 1000 rooms. in that hostel only even no r used for room no'i.e. the room no r 2,4,6.........1998,2000.all the rooms have one resident each.one fine morning , the warden call all the resident & ...

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tanweer_ahmad Saysyeah this problem is from CL fundabook just look out for the answer at the back

dear tanweer ,

please check the date of the last post.no point in shaking up 9 month old threads.

enjoy

rohit

Mods, pls lock..

yeah this problem is from CL fundabook just look out for the answer at the back

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@ganeshiyer
42

here is a problem on a ar

in a big hostel,there r 1000 rooms. in that hostel only even no r used for room no'i.e. the room no r 2,4,6.........1998,2000.all the rooms have one resident each.one fine morning , the warden call all the resident & tell them 2 go back to their room as well as the multiples of their room no's. when a guy visit a room & finds the door open,he closes it& if the door is closed,he opens it.all 1,000 guys do this operation . all the doors were open initially.

1. the last room that is closed is room no???

2 tha 38th room that is open is room no???

3if only 500guys i.e. resident of room no 2 to 1000 do this task,then the last room that is closed is room no

4in the above(3) case, how many rooms will b closed in all

5 if u r a lazy person, u would like 2 stayin a room whose no is

a. more than 500

b more than 1000

c 500

d 2000

plz solve it

initially all doors are open.

hence they will be closed at the end when they are manipulated odd no of times.

i.e odd no. persons should enter or leave it......and hence should have odd no. of even factors

here all nos can be xpressed as ....

2^a*p^b..... or 2^a*p1^b*p2^c where p,p1 p2 are prime.

here we will have odd no. of even factors when

a.....odd

and b....even ..... for first case

and

a..... odd

and b and c....even.......... for second case

the maximum value is 2*5^2*3^2=1800 ...[ this is also the minimum value for 2nd case]

the maximum value will be the last door to close.

the first 38 doors are from 2 to 76

out of these doors of the form 2^a*p^b where

a.....odd

and b....even

will be closed and all others will be open.

there are 6 such nos

they are

2, 2*3^2, 2*5^2, 2^3, 2^3*3^2, 2^5

hence we have to add six more nos [and also verify whether any of these is closed]

hence the no. will 88.

here the maximum no. is 512

here maximum no is 2^9*3^0

guys in room no 1002 to 2000 will have to enter omly there rooms

because the nearest multiple of 1002 is 2004 and no such room exists

hence ans : b

the method here is really time consuming. any other short-cut methods are welcome

p.s: anubond6 ,can post the method from cl study material, atleast the logic.

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@anubond6
48

hey guyz this prob is of cl stdy materiaL from analytical reasoning funda book.y don u luk out at d sol. given at the back.

Im back again:2gunfire:

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here is a problem on a ar

5 if u r a lazy person, u would like 2 stayin a room whose no is

a. more than 500

b more than 1000

c 500

d 2000

plz solve it

ans is option a

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@linnet
2

in a big hostel,there r 1000 rooms. in that hostel only even no r used for room no'i.e. the room no r 2,4,6.........1998,2000.all the rooms have one resident each.one fine morning , the warden call all the resident & tell them 2 go back to their room as well as the multiples of their room no's. when a guy visit a room & finds the door open,he closes it& if the door is closed,he opens it.all 1,000 guys do this operation . all the doors were open initially.

1. the last room that is closed is room no???

2 tha 38th room that is open is room no???

3if only 500guys i.e. resident of room no 2 to 1000 do this task,then the last room that is closed is room no

4in the above(3) case, how many rooms will b closed in all

5 if u r a lazy person, u would like 2 stayin a room whose no is

a. more than 500

b more than 1000

c 500

d 2000

plz solve it

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