Official Quant thread for CAT 2013

@bs0409 said:
OA-12A triangle is divided into four partsby two straight lines from two corners. the areas of three parts are 8 , 5 , 10..find the area of fourth part
it's 22
applied ladder theorem..
1/A + 1/B = 1/C + 1/D


drop perpendiculars and find A,B ,C..in terms of base.
D is for the fourth one which we need to find..
will come up with a figure later..
@iLoveTorres said:
@scrabbler isnt option E less than 1.. its approx .8 in value..
rt (8 - 4*1.73) = rt (8 - 6.92) = rt (1.08) roughly. Just more than 1. See the figure I had attached earlier, just more than 1 is what we need.

regards
scrabbler

@ChirpiBird said:
it's 22applied ladder theorem.. 1/A + 1/B = 1/C + 1/Ddrop perpendiculars and find A,B ,C..in terms of base. D is for the fourth one which we need to find..will come up with a figure later..
That is only for one config of 8, 5, 10; any three of the four places could be 8, 5, 10, giving multiple possible cases...figure needed for unique answer.

regards
scrabbler

@scrabbler said:
That is only for one config of 8, 5, 10; any three of the four places could be 8, 5, 10, giving multiple possible cases...figure needed for unique answer.regardsscrabbler
No.. it's for all cases i think. Change in orientation will simply change the view. as in paper tilt kar k dekhoge toh same dikhega! let me try.. again. in differnt orientation.

btw ..i m lousy in making figures, will make one in paint of what i did. gimme 10min ..
@ChirpiBird said:
it's 22applied ladder theorem.. 1/A + 1/B = 1/C + 1/Ddrop perpendiculars and find A,B ,C..in terms of base. D is for the fourth one which we need to find..will come up with a figure later..
yaar samajh nahi aaya......
@ChirpiBird said:
No.. it's for all cases i think. Change in orientation will simply change the view. as in paper tilt kar k dekhoge toh same dikhega! let me try.. again. in differnt orientation.btw ..i m lousy in making figures, will make one in paint of what i did. gimme 10min ..
Here's my take...tell me if I am doing anything wrong according to what the problem asks?

regards
scrabbler

@mailtoankit , @scrabbler :
Ladder theorem states that if there are two ladders resting on two walls and intersecting at a point, then the reciprocal of the perpendicular drawn from the point of the intersection of the ladders is equal to the sum of the reciprocal of the height of the walls( height of the wall is till the point where the ladder meets the wall).


rest explanation is in figure...

@ChirpiBird said:
@mailtoankit , @scrabbler :Ladder theorem states that if there are two ladders resting on two walls and intersecting at a point, then the reciprocal of the perpendicular drawn from the point of the intersection of the ladders is equal to the sum of the reciprocal of the height of the walls( height of the wall is till the point where the ladder meets the wall).rest explanation is in figure...
But that still doesn't explain how you have assigned the 3 given values to the regions of the figure. That is not unique...there will be some 6 or 12 arrangements depending on your interpretation (I have shown 3 in the attachment I made)...

regards
scrabbler

@scrabbler said:
But that still doesn't explain how you have assigned the 3 given values to the regions of the figure. That is not unique...there will be some 6 or 12 arrangements depending on your interpretation (I have shown 3 in the attachment I made)...regardsscrabbler
bro this question can only be solved if you look at it wrt to the symmetry of geometrical figures. i tried my share of luck but i am not able to proceed. hope you come out with a simplified answer. do tag me if you find a solution to this question :)
@scrabbler said:
But that still doesn't explain how you have assigned the 3 given values to the regions of the figure. That is not unique...there will be some 6 or 12 arrangements depending on your interpretation (I have shown 3 in the attachment I made)...regardsscrabbler
The fig must be given, otherwise we get different answers.
Perhaps, i just got lucky! :D
@ChirpiBird said:
The fig must be given, otherwise we get different answers. Perhaps, i just got lucky!
i jus got a siite where the same question is done and the answer is shows to be 22.. but no explanation is given as to why a particular arrangement of 5,8,10 is used
@iLoveTorres said:
i jus got a siite where the same question is done and the answer is shows to be 22.. but no explanation is given as to why a particular arrangement of 5,8,10 is used
It is a standard question....with the figure given. Someone probably tried to make the question tougher by removing the figure and just giving a description, not realising that this would introduce ambiguity. Idiot.

A bit of googling led me to this; scroll down a bit to find the same puzzle.

http://2000clicks.com/mathhelp/geometrytrianglecrossedladder.aspx

regards
scrabbler

@scrabbler looks like this question has been put up on pagalguy even last year.. also on total gadha.. but its quite ambiguous as no one knows as to why the answer is 22.. every seeem to be happy arriving at the answer without knowing the logic behind it :)
@iLoveTorres said:
@scrabbler looks like this question has been put up on pagalguy even last year.. also on total gadha.. but its quite ambiguous as no one knows as to why the answer is 22.. every seeem to be happy arriving at the answer without knowing the logic behind it
That's not unusual 😛 I prefer to know the reasons why a solution works, but even I fall into the same trap often enough, seeing a problem that looks familiar and not checking for "uniqueness" or whatever...there's always more to learn. You stop improving when you're dead, I guess.

regards
scrabbler

@scrabbler said:
That's not unusual I prefer to know the reasons why a solution works, but even I fall into the same trap often enough, seeing a problem that looks familiar and not checking for "uniqueness" or whatever...there's always more to learn. You stop improving when you're dead, I guess.regardsscrabbler
just the way my ignorance in that triangle inscribed in a square question. I knew that the answer has to be between 1 and 1.414 but was lazy to calculate the final option 😃
@iLoveTorres said:
just the way my ignorance in that triangle inscribed in a square question. I knew that the answer has to be between 1 and 1.414 but was lazy to calculate the final option
And I did so, only because I had seen a very similar problem before. That's why solvng a lot of questions helps I guess...database bada ho jaata hai!

regards
scrabbler

" Remove all the cards except aces and kings from a deck. From this, deal two cards to a friend. If she looks at her cards and announces (truthfully) that her hand contains an ace, what is the probability that both her cards are aces? If she announces instead that one of her cards is the ace of spades, what is the probability then that both her cards are aces? "
@iLoveTorres said:
" Remove all the cards except aces and kings from a deck. From this, deal two cards to a friend. If she looks at her cards and announces (truthfully) that her hand contains an ace, what is the probability that both her cards are aces? If she announces instead that one of her cards is the ace of spades, what is the probability then that both her cards are aces? "
Is it 3/11 and 3/7? Will type out detailed answer if correct...feeling lazy now :)

regards
scrabbler

@scrabbler said:
Is it 3/11 and 3/7? Will type out detailed answer if correct...feeling lazy now regardsscrabbler

@iLoveTorres
I think ans would be 3/14 and 3/7
@pavimai said:
i am also not sure about this question..it do confused me
@Logrhythm said:
all number of form 9k between 1000 and 10000AP bana lo... 1008, 1017,...,9999so total = (9999-1008)/9 + 1 = 1000 numbers...@pyashraj bhai...shouldn't it be like this...?? or am i missing somethig?? side effects of PG from office
1 x y z 2 x y z 3 x y z 4 x y z 5 x y z 6 x y z 7 x y z 8 x y z 9 x y z

x+y+z=8 x+y+z=7 x+y+z=6 x+y+z=5 x+y+z=4 x+y+z=3 x+y+z=2 x+y+z=1 x+y+z=0
10c2 9c2 8c2 7c2 6c2 5c2 4c2 3c2 2c2

45+36+28+21+15+10+6+3+1=165