Official Quant thread for CAT 2013

@catter2011 said:
P works faster than q. Will he take more than 20 days to complete a job X ?1) The sum of times that p and q would take to complete X is 50 days2) p would take 10 days less than q to complete xopitons:a)If the data in St1 alone is sufficient while data in st2 alone is notb)data in st2 alone is suffice , while data in st1 alone is notc)if the data in st1 alone or st2 alone but not bothd)if the data in both the st's together is suffice to answer the questione)if the data even in both the st's together is not suffice to answer the question
Is it option d) ?

@bullseyes
@krum

My take is also a) but TIME says its d).. Krum pls explain..



@krum I agree.." but from st1 p and q takes 50 days.. then by any means.. p will take more than 50 days to complete tht work.. assuming b doesnt do a negative work.. " am i flawed in the quoted lines any wer ?
@krum 1/P + 1/Q = 1/50 => P,Q>=50
@catter2011 said:
@krum I agree.." but from st1 p and q takes 50 days.. then by any means.. p will take more than 50 days to complete tht work.. assuming b doesnt do a negative work.. " am i flawed in the quoted lines any wer ?
No it does'nt say like that !! the no. of days taken by p + no. of days taken by q = 50 days !! thats what it says !!
@kingsleyx converting his words to expression...

1/P + 1/Q = 1/50 => P,Q>=50 ??
@catter2011 said:
@bullseyes@krumMy take is also a) but TIME says its d).. Krum pls explain..
It will be d.

St1: p+q =50 and p is faster than q. u can have 24+26 OR 19 + 31. In both the cases P is faster but >20 in first case and
combine St2 and ull get the answer.
Hence D
@catter2011 said:
@krum I agree.." but from st1 p and q takes 50 days.. then by any means.. p will take more than 50 days to complete tht work.. assuming b doesnt do a negative work.. " am i flawed in the quoted lines any wer ?
@kingsleyx said:
No it does'nt say like that !! the no. of days taken by p + no. of days taken by q = 50 days !! thats what it says !!
^ thats what i think too
Find the sum of all positive integers m such that m^2 + 25m + 19 is
a perfect square?

a) 125
b) 130
c) 159
d) 164
e) 198
@catter2011 said:
@kingsleyx converting his words to expression...1/P + 1/Q = 1/50 => P,Q>=50 ??
does my expression is wrong ?

@krum
@Ibanez
@kingsleyx
@bullseyes
by common sense also. if both took 50 days, den individually each will definitely take more than 50 days to complete tht work...
@catter2011 said:
@kingsleyx converting his words to expression...1/P + 1/Q = 1/50 => P,Q>=50 ??
"The sum of times that p and q would take to complete X is 50 days" is different from "the time taken by them working together " !! If its the second, then ur equation is absolutely right but I guess it means the first here. correct me if I am wrong !
@catter2011 said:
does my expression is wrong ?@krum@Ibanez@kingsleyx@bullseyesby common sense also. if both took 50 days, den individually each will definitely take more than 50 days to complete tht work...
That expression is wrong. Question does not state that they together take 50 days to complete the work. It states that the number of days taken by P + number of days taken by Q = 50.Interpret it like that
@catter2011 said:
pls share the approach for this question guys..what is the product of 6843256709 and 125 ?855407088625855407087625855400788625855407088525855407089625
the digit sum comes out to be 4.. only a & d satisfy this. now last 3 digit of both are 625 and 525. think a lil abt divisibility of 125 and u get ur answer as "a"
@Ibanez
p+q = 50
also
p
=> 50-p > p or p
but to conclude further we need statement b as well..
hence the answer is d
@nick_baba said:
Find the sum of all positive integers m such that m^2 + 25m + 19 isa perfect square?a) 125 b) 130c) 159 d) 164 e) 198
164 , values 125,5,34
@kingsleyx
@Ibanez thanks puys..

got it.. ur fst expression is correct.. its sum of their individual periods.. not taken together to complete the work..


@onlytj said:
164 , values 125,5,34
yup..correctia..:drink:

@staaalinnn said:
Q> Let a, b, c, d be four real numbers such that a + b + c + d = 8 & ab + ac + ad + bc + bd + cd = 12. Find the greatest possible value of d.
To maximize d , a=b=c => 3a+d=8, from second eqn we get 12= 3a^2 + d(8-d)
=> combining above eqns we get d^2-4d+14=0 => d= 2+3 root(2)
@bullseyes said:
the digit sum comes out to be 4.. only a & d satisfy this. now last 3 digit of both are 625 and 525. think a lil abt divisibility of 125 and u get ur answer as "a"
*1000/8 is better approach...
@nick_baba said:
Find the sum of all positive integers m such that m^2 + 25m + 19 isa perfect square?a) 125 b) 130c) 159 d) 164 e) 198
m^2 + 25m + 19=n^2
=>m^2+(25/2)^2+2*25/2*m+19-(25/2)^2=n^2
=>4m^2+25^2+100m+76-625=4n^2
=>(2m+25)^2-549=4n^2
=>(2m+25-2n)(2m+25+2n)=549=1*549=3*183=9*61
=>m=125/34/5

125+34+5=164