[Vineetverma]

Originally Posted by naren_aumech

2. I think the answer is 9C2 * 9C2
3. Total numbers possible = 9000
Numbers with all digits distinct = 9*9*8*7
numbers with one or more repeating digits = 9000 - 4536 = 4464
4. 19!/(6!*8!*5!)

Working on the others...

bro for 3 shudnt the max outcomes be 10000 (since it is a phone no. assuming i can start with 0)

so (10000 - 10x9x8x7) / 10000

[Vineetverma]

Originally Posted by crack_2009

2. is it 49????

Originally Posted by naren_aumech

2. I think the answer is 9C2 * 9C2
3. Total numbers possible = 9000
Numbers with all digits distinct = 9*9*8*7
numbers with one or more repeating digits = 9000 - 4536 = 4464
4. 19!/(6!*8!*5!)

Working on the others...

Originally Posted by Vineetverma

is any1 gettin the same ans

1) 64c1 x 42c1
2) 9c2 x 9c2 (not sure) = 1296 (cant understand the qn prop)
3) (4960) / 10000
5) 19 c 9

Originally Posted by abhay15783

my take on this
3!*6!*8!*5!

arranging the different languages book in 3! ways and then arranging them among themselves

Originally Posted by Kashyap Rastogi

2) 1296
3) 4464/9000
5) 20C10 * 10!

What are the correct answers??

Originally Posted by naga25french

these question can be done easily when one goes through sandeep sen full material.. i guess u have taken it from that material only

will update ma answers soon!

Originally Posted by Vineetverma

bro for 3 shudnt the max outcomes be 10000 (since it is a phone no. assuming i can start with 0)

so (10000 - 10x9x8x7) / 10000

@crack 2009 plz post ur approach i am gettin 1296 thnks!!!

@naren plz share the approach for solvin qn no4 thnkx buddy

@ vineet ppl will kill u coz u never have the answers

@ abhay plz throw some light on ur approach thnks mate!!

@ kashyap plz explain qn 5 i m gettin diff ans

@ naga guilty as charged!!!! sab kuch kar liya kya yaar qn bhi yaad ho gaye

edit: 1) naga plz explain qn no. 4
2) sandeep sens material http://www.cse.iitd.ernet.in/~ssen/c...background.pdf

[Kashyap Rastogi]

Originally Posted by Vineetverma

@ kashyap plz explain qn 5 i m gettin diff ans

Selecting 10 sections out of 20= 20C10 ways
Assigning 10 sections to 10 students= 10 ! ways

I am very bad at P&C and probability. So, a high PROBABILITY of me being wrong...

[naga25french]

Originally Posted by Vineetverma

@ naga guilty as charged!!!! sab kuch kar liya kya yaar qn bhi yaad ho gaye

edit: 1) naga plz explain qn no. 4
2) sandeep sens material http://www.cse.iitd.ernet.in/~ssen/csl356/notes/background.pdf

i dont understand hindi that much

anyways for 4th

3! * 5! = 360 ways

[Kashyap Rastogi]

Originally Posted by naga25french

i dont understand hindi that much

anyways for 4th

we can select a particular kind of books by selecting 1 ,2,3,4 ,etc

what i am trying to say is 6 french book means , he can select 1,2,3,4,5,6

in 2^6 - 1 ways

similiarly, other two in 2^8 - 1 ways and 2^5 - 1 ways

so now multiply

3! * 31 * 63 * 255

ps : i am trying the problem set for the first time .. have gone through that book few months back.. completely lost track

Can you please explain why do we have to select any books. i see this question as a permutation problem, rather than a combination problem, as here books are to be arranged and not selected. My take-
Arranging 3 sets of books- 3! ways
Arranging books within sets- 6! * 8! * 5!

Please tell me where am i wrong??

[Vineetverma]

Originally Posted by naga25french

ma answers :

1) 64*36/2! = 32*36 = 1152

@ naga shud it be 64c1 x 36c1 ??

[naga25french]

Originally Posted by Vineetverma

@ naga shud it be 64c1 x 36c1 ??

think how will u select 2 square in chess board.. it will be 64C2 and not 64 * 63

hope u got the catch on that

[brajesh.pandey]

P Q R can do a job in 6 hrs,,7 hrs and 14 hrs respectively.They start to work together at 10:00 am. P left after 2 hours Q left 20 minutes before the completion of work.

When did they finish the work>
1>1:20 pm
2>1:40 pm
3>2:20 pm
4>2:40 pm

Please help with a detailed solution?

[naren_aumech]

Originally Posted by Vineetverma

@crack 2009 plz post ur approach i am gettin 1296 thnks!!!

@naren plz share the approach for solvin qn no4 thnkx buddy

@ vineet ppl will kill u coz u never have the answers

@ abhay plz throw some light on ur approach thnks mate!!

@ kashyap plz explain qn 5 i m gettin diff ans

@ naga guilty as charged!!!! sab kuch kar liya kya yaar qn bhi yaad ho gaye

edit: 1) naga plz explain qn no. 4
2) sandeep sens material http://www.cse.iitd.ernet.in/~ssen/c...background.pdf

Sorry dude my answer for qn. no 4 was wrong... but I thought it should be 3!*8!*6!*5!... But naga's answer differs... Machi Naga... pls explain...

[Vineetverma]

Originally Posted by brajesh.pandey

P Q R can do a job in 6 7 and 14 days respectively.They start to work together at 10:00 am. P left after 2 hours Q left 20 minutes before the completion of work.

When did they finish the work>
1>1:20 pm
2>1:40 pm
3>2:20 pm
4>2:40 pm

Please help with a detailed solution?

srry but can u comfirm that the qn says 6 , 7 , 14 days thnx man!!

edit if it is hrs then 1 : 20 pm

heres hw!!

let the total wrk be 42 (lcm of 6 , 7 , 14)

p does 42 in 6 hrs so in 1 hr = 7
q = 6
r = 3

so they wrk 2gther fr 2 hrs
means 7+6+3 their combined efficiencies ie 16 x 2 = 32 ---(1)

now since q leaves 20 mins befor completion r must ve completed the job in those 20 mins r does 3x wrk in 1 hr so 20 min = 3/3 = 1x work

42 - 1 = 41
p left at 32
so 41 - 32 = 9 / (6 + 3)
hence 1 hr
so 2 + 1 + 1/3 hrs