# @enigma2011

##### 48 karma
###### CATOfficial Quant Thread for CAT 2011 [Part 4]
If a and b are roots, then
ab = 1/(I - m) = 2a^2
a + b = I/(m - I) = 3a

=> 2I^2/9(I - m)^2 = 1/(I - m)
=> 2I^2 - 9I + 9m = 0

=> 81 - 72m 0

=> m 9/8

Chill bhai can you please xplain the part in Bold., Are I & M simple variables?
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###### CATOfficial Quant Thread for CAT 2011 [Part 4]
Ohh and help for this question as well

Q.In a packing unit of a chemical factory,one machine fills the bottles at rate of 25 bottles per min & needs to be switched off for 10 mins after filling every 500 bottels.Another machine can seal the filled bottles at the rate of 400 bottles per min & needs to be switched off for 5 mins after every 400 bottles. If both the machines start at the same time, that is 8 am, find the earliest time at which 4000 packed & sealed bottles will be ready for delivery?
a)12:10
b)12 noon
c)12:05
d)11:50

(I got 12:10 but the correct answer is 12:05)

Hey one doubt, do the sealing rate is 400 bottles per minutes? I m getting none of these:shock:
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###### CATOfficial Quant Thread for CAT 2011 [Part 4]
Xane Says
7^3 = 343... so 3 must be te 12th digit from left.. or 1st from right..

Hey Jainbhai and Xane.. dint understand how its 3. whats the catch here?:banghead:
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###### CATOfficial Quant Thread for CAT 2011 [Part 4]

1..The number of quadratic eqns which are unchanged by squaring their roots =
a..2 b..4 c..6 d..none of these

Plz post the approach too

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###### CATCAT 2011 Exam Dates

hey puys.. CAT Registration has just begun . Please post your dates and location!! The Countdown begins.. ATB!!!!

• 8 Likes
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###### CATOfficial Quant Thread for CAT 2011 [Part 3]
gs4890 Says
answer has to be cbd. there are so many possibilities bhai and how did u come out to know that rohan's current age is 14.

same doubt.. Puys how can we be sure that his age is 14? Did i miss out on any part of the question?
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###### CATOfficial Quant Thread for CAT 2011 [Part 3]
Draw venn diagram and check for people who are reading BT+BI. these are 12. we remove them and move them to BI+BW category.
remaining will come from BT ONLY category.

total people not reading BI or BW = 300 - (207 +4) = 99

not in options. Not sure what went wrong.
Can anyone check?

Is the Venn correct.. I guess the question should be how many read BI & BW
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###### CATOfficial Quant Thread for CAT 2011 [Part 3]

Q2) If 16 of the respondents who were reading Business Today ,stop reading Business Today and instead start reading Business world , then what is the maximum number of respondents who will not be reading Business India and Business World

(1) 59
(2)55
(3)75
(4) 63

plzz postr the approach as well

Are you sure its 'who will not"? I getting a answer of 59 if the question is "who will be"..
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###### CATOfficial Quant Thread for CAT 2011 [Part 3]
Krazy_me Says
Bhai, can you please explain the bold part? Didn't get!

Arithmetic mean > Geometric Mean..

As x,y,z are in AP y=(x+z)/2

three numbers : AM=(x+y+z)/3....(i)
GM= (xyz)^1/3 .....(ii)

substitute x+z=2y in (i) and xyz=4 in (ii).

We get 3y/3 > 4 ^(1/3)

Hope its clear..

P.S : There are my first few quant posts. Please bear with me puys..
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###### CATOfficial Quant Thread for CAT 2011 [Part 3]
puys pls solve this sum..
m not getting it

given xyz = 4 and xyz are in AP.. As xyz are in AP and so 2y= x+z ..

For any series we know AM>=GM..
Hence (x+y+z)/3 >= (xyz)^1/3

3y/3>4^(1/3)

y>= 2^(2/3)..

Whats the OA?
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