Official Quant thread for CAT 2013

@amresh_maverick said:
A,B,C,D, E, F, G can stand in 7! ways .requirement is : CDB - can be arranged in 3! ways but only one is acceptableHence total ways = 7!/3!PS: galat hone ke pure assaar hain
Dekhte hain baki janta kya bolti hai tumhare asaar ke bare me:)

Team BV - Vineet
@bodhi_vriksha said:
In how many ways can A,B,C,D, E, F, and G stand in queue such that D is always behind B and C is always behind D?Team BV - Vineet
CDB can be arranged in 3! ways but we want only 1 combination out of those.

So, Total Combinations / 3! = 7!/3! = 840 ways.
Good job Amresh and Estallar12.

Try this one now...

The equation |z-1| - |z-2| + |z-4| = k has exactly r real solutions for some real k. Then which among the following relations between k and r can not be true?

(a) k/r = 3/5 (b) k = r (c) k/r = 3/2 (d) k/r = 5/3 (e) k = r-1



Team BV - Vineet
@bodhi_vriksha said:
In how many ways can A,B,C,D, E, F, and G stand in queue such that D is always behind B and C is always behind D?Team BV - Vineet
choose 3 people c,d,b in 7C3 ways..and arrange d remaining 4 people in 4! ways...so it gives 7C3*4!=840
@bodhi_vriksha said:
In how many ways can A,B,C,D, E, F, and G stand in queue such that D is always behind B and C is always behind D?Team BV - Vineet
sabko pata hai..phir bhi 7!/3! ..
@bodhi_vriksha said:
Good job Amresh and Estallar12.Try this one now...The equation |z-1| - |z-2| + |z-4| = k has exactly n real solutions for some real r. Then which among the following relations between k and r can not be true?(a) k/r = 3/5 (b) k = r (c) k/r = 3/2 (d) k/r = 5/3 (e) k = r-1Team BV - Vineet
My solution :

Z1--------Z-1=k
2
Z>4------------Z-3 =k

what now sir ?
@amresh_maverick said:
My solution :Z12 Z>4------------Z-3 =kwhat now sir ?
same here..is step k baad samaj hi nahi aa raha
@amresh_maverick said:
My solution :Z12 Z>4------------Z-3 =kwhat now sir ?
@mohitjain said:
same here..is step k baad samaj hi nahi aa raha

HINT : Use modulus function to solve .. It is a one liner after that :)

Team BV--Pratik Gauri
@bodhi_vriksha said:
Good job Amresh and Estallar12.Try this one now...The equation |z-1| - |z-2| + |z-4| = k has exactly n real solutions for some real r. Then which among the following relations between k and r can not be true?(a) k/r = 3/5 (b) k = r (c) k/r = 3/2 (d) k/r = 5/3 (e) k = r-1Team BV - Vineet
k/r = 3/2 nahin aa raha hai...

Edit: n aur r mein confusion ho raha hai....please clarify....maine k aur n mein nikala actually....r ka importance kuch samajh nahin aaya

regards
scrabbler

@mohitjain said:
same here..is step k baad samaj hi nahi aa raha
@amresh_maverick said:
My solution :Z12 Z>4------------Z-3 =kwhat now sir ?

Please check your critical points again. The intermediates one should correspond to 1 .

Hint: What all range of values can k take in these intervals?

Team BV - Vineet

@bodhi_vriksha said:
Good job Amresh and Estallar12.Try this one now...The equation |z-1| - |z-2| + |z-4| = k has exactly n real solutions for some real r. Then which among the following relations between k and r can not be true?(a) k/r = 3/5 (b) k = r (c) k/r = 3/2 (d) k/r = 5/3 (e) k = r-1Team BV - Vineet
Is it Option C by any chance ? :roll:
@scrabbler said:
k/r = 3/2 nahin aa raha hai...Edit: n aur r mein confusion ho raha hai....please clarify....maine k aur n mein nikala actually....r ka importance kuch samajh nahin aayaregardsscrabbler
@Estallar12 said:
Is it Option C by any chance ?
Exactly. Couldn't quite understand the variables. k and z is fine! Now n and 'r' ? :roll:
@Estallar12 said:
Is it Option C by any chance ?
Let all the puys attempt . Then i'l post the solution. It's a one liner using MOD function . Else it would take time :)

Team BV--Pratik Gauri
@Estallar12 said:
Exactly. Couldn't quite understand the variables. k and z is fine! Now n and 'r' ?
Yes k and r mein sab satisfy aa rahe the.... so tried k and n and I think (c) works... graphically kiya so not sure...

regards
scrabbler

@Estallar12 said:
Exactly. Couldn't quite understand the variables. k and z is fine! Now n and 'r' ?

Guys, assume 'r' in place of that 'n'. There was a typo in the problem statement.

Team BV - Vineet
@bodhi_vriksha said:
In how many ways can A,B,C,D, E, F, and G stand in queue such that D is always behind B and C is always behind D?Team BV - Vineet
Correct Answers: - 840 ways

1st method: - Out of 7 persons, we need to choose 3 and we can arrange them only 1 way. (like C>D >B) and remaining 4 persons, we can arrange 4! ways.
Total number of ways = C (7, 3) x 1 x 4! = 840.

2nd method: - CDB can be arranged in 3! ways but only 1 combination is in our favour.
So, Total Combinations (without any condition) = 7!
Required combinations = 7!/3! = 840.
@scrabbler said:
k/r = 3/2 nahin aa raha hai...Edit: n aur r mein confusion ho raha hai....please clarify....maine k aur n mein nikala actually....r ka importance kuch samajh nahin aayaregardsscrabbler
Yes scrabbler. There was a typo, which i have edited. Check the problem now.

Team BV - Vineet
In a multinational company, the employee ID is a three-digit number (first digit is non-zero). However, no two employees can have IDs that are identical when written in reverse order (123 and 321 are identical and hence only one of them can exist). What is the maximum number of employees that can use this coding system?
450,495,540 ?
@bodhi_vriksha said:
Yes scrabbler. There was a typo, which i have edited. Check the problem now.Team BV - Vineet
Then the answer is what I said earlier? 3/2? Assuming that is the only change...

regards
scrabbler

@Estallar12 said:
Is it Option C by any chance ?
How did you solve it Estallar?

Team BV - Vineet