Official Quant thread for CAT 2013

MBA CAT 2024
15343
@raopradeep said:
find maximum value of 6x - x^2 +7 if |x-4|>=2a)14b)15c)16d)17

x belongs to ( -infinite ,2 ) U ( 6, infinte )
max is obtained by differentiating and equating to zero ..
==> 6-2x=0 ==> x=3..which cannot be the value of x ..because 3 doesnot belong to its domain..

so ...write like dis... x (6-x) + 7 ..x=1 its 12 ...x=2...15....so 15 is the max... i did some mistake earlier @raopradeep
15344
@raopradeep said:
find maximum value of 6x - x^2 +7 if |x-4|>=2a)14b)15c)16d)17
16?
15345
@shinoda said:
a right circular cylinder has to be made out from a metal sheet such that sum of its height and radius does not exceed 9 and it has max volume possible..?
r+h=9. So r= 9-h. Max volume possible for cylinder is found out by differentiating pi*(9-h)^2*h. let V= pi*(9-h)^2*h and find V' using product rule of diffrentiation to get h =9 or 3.
For h=3 and r =6 we get max value for cylinder which is 108*pi


15346
@ravi.theja said:
16??
plz explain but OA is 15
15347
@mailtoankit said:
16?
OA is 15
but how to appeoach it plz explain ..
15348
@raopradeep said:
plz explain but OA is 15
edit chesa..chuduu :)
15349
@pirateiim478 said:
r+h=9. So r= 9-h. Max volume possible for cylinder is found out by differentiating pi*(9-h)^2*h. let V= pi*(9-h)^2*h and find V' using product rule of diffrentiation to get h =9 or 3.For h=3 and r =6 we get max value for cylinder which is 108*pi
do u know any other method sans differentiation ??
15350
@ravi.theja
@ravi.theja said:
x belongs to ( -infinite ,2 ) U ( 6, infinte ) max is obtained by differentiating and equating to zero .. ==> 6-2x=0 ==> x=3..which cannot be the value of x ..because 3 doesnot belong to its domain..so ...write like dis... x (6-x) + 7 ..x=1 its 12 ...x=2...15....so 15 is the max... i did some mistake earlier @raopradeep
thanks
15351
@raopradeep said:
OA is 15 but how to appeoach it plz explain ..
haan yaar...its 15 only...
for x = 2
6(2)-(2)^2+7 = 15

16 ....x = 3 ke liye kiya tha...but |x-4|>=2 does not satisfy
15352
@shinoda said:
do u know any other method sans differentiation ??
@pirateiim478 anna h :r = 1:2 unte max vasthada??

@shinoda i guess i has to be lik h: r = 1:2 to get volume as maximum possible
15353

can anyone please post detailed sol of this question -


Q. Number of 5 digit numbers with only 3 distinct digits.

Thanks
15354
@ravi.theja said:
@pirateiim478 anna h :r = 1:2 unte max vasthada??@shinoda i guess i has to be lik h: r = 1:2 to get volume as maximum possible
Yes h:r =1:2 vunte max vastadi for cylinder.
@coonal2006 said:
can anyone please post detailed sol of this question -Q. Number of 5 digit numbers with only 3 distinct digits.Thanks
1512??
15355
@coonal2006
iska OA to bta
15356
@ishu1991 said:
@coonal2006iska OA to bta
I don't have its options..maybe if you can post your method we can discuss it...
15357

A square piece of paper is folded so that 1/2 the paper covers the other completely ( so now the folded paper appears as a rectangle whose one side is twice that of the other). This is again folded to give the appearance of a square( with dimensions half of original square paper). Now this square is folded again along the diagnol and again wrt the altitude from right angle to the hypotenuse of the rt angled triangle formed. the paper is then unfolded completely. Find the max no of triangles formed

15358
@pirateiim478 said:
Yes h:r =1:2 vunte max vastadi for cylinder. 1512??
approach??
15359
@coonal2006 said:
can anyone please post detailed sol of this question -Q. Number of 5 digit numbers with only 3 distinct digits.Thanks
20,880??
15360
@ravi.theja said:
20,880??
can you plz post ur approach..my answer is 16,872
15361
@coonal2006 said:
approach??
If i understoof correctly only 3 distinct digits in 5 digit no means other 2 numbers must be repeated from these 3 distinct numbers.

If 5 digit no doesnt start with 0 => 9*8*7*3c2
If If 5 digit no starts with 0 =>8*8*7*3c2
Total = 2856 numbers//
15362
@coonal2006 said:
can you plz post ur approach..my answer is 16,872
with out having a zero in the selected 3 numbers... its 10C3 *[3c1* 5!/3! + 3C2*5!/2! * 2! ]

am trying the cases including zero in the selected 3 digits..i ll edit it aftr i get...

There are total of 200 cases if 0 is included ... so its 10C3 *[3c1* 5!/3! + 3C2*5!/2! * 2! + 200 ]

@coonal2006 edited check it