Official Quant thread for CAT 2013


@albiesriram said:
(9x²Sin²x + 4)/(xsinx) = 9xSinx + 4/(xSinx)

Here significance of 0 9xSinx and 4/(xSinx) are positive

This means we can use AM ≥ GM, as product of 9xSinx and 4/(xSinx) is 36 (a constant)

Using this we will get the least value as 12
@albiesriram said:
One more geometry ,
This question went unsolved yesterday... @scrabbler @chillfactor

two more counting problems..

1)



@albiesriram said:
two more counting problems..1)
1st 115?

Either I pick one each from 3 different sides (which can be done in 1*2*3 + 1*2*4 + 1*3*4 + 2*3*4 = 50 ways) or else 2 from 1 side and one from any other (2C2 * 8 + 3C2 * 7 + 4C2 * 6 = 65 ways) total 50 + 65 = 115.

Previous problem ka kuch idea nahin hai 😃 Will try it again after a while....

regards
scrabbler

@albiesriram I think we can not add all the numbers in that digit by that summation formula of 'n' natural numbers. Like the addition of (1,2,3,4,.....,9,1,0,1,1,1,2,1,3,.... ) can not be determined by that addition formula.
@albiesriram said:
two more counting problems..1)
115??

10c3 - (4c3 + 3c3) = 115

"In triangle ABC, the angle subtended by side BC at the orthocenter is 100 degrees, find the angle subtended by BC at the incenter."


Can I have a diagram too, please.
@albiesriram said:
two more counting problems.. 1)
Total number of ways = Taking two points from each side + Taking one point from each side = {8+3C2*7+4C2*6} +{2*3*(4+1) + 1*4*(2+3)}= 115

Team BV - Vineet
@veertamizhan said:
"In triangle ABC, the angle subtended by side BC at the orthocenter is 100 degrees, find the angle subtended by BC at the incenter."Can I have a diagram too, please.
Do you have an OA? I am getting 100 only...fig thoda time lagega...in office :(

Edit: getting 130!

regards
scrabbler

@Gsathe89 said:
find the remainder when 123456789101112.....40 is divided by 36???/
4a=9b+1=> 0=(b+1)(mod4) (since a is an integer)=>min(b)=3. Hence the remainder =9*3+1=28

Team BV - Vineet
@scrabbler no I don't have OA(?)

the answer is 125 saar.
Q: 107^109^101 div 111 R?
@albiesriram said:
12
@albiesriram said:
two more counting problems..1)
10C3-4C3-3C3=115
with 2 and 1 dot triangle is not possible hence not req to consider
@soham701 said:
@albiesriram I think we can not add all the numbers in that digit by that summation formula of 'n' natural numbers. Like the addition of (1,2,3,4,.....,9,1,0,1,1,1,2,1,3,.... ) can not be determined by that addition formula.
We are going to split 12345678910 like

1|2|3|4|5|6|7|8|9|10|11|12| .. and not by single digits.
divisibility rule for 9 allows such partition. coz (10^n-1) is divisible by 9.
we can partition a number according to tour need in case of 9.
@viewpt said:
Q: 107^109^101 div 111 R?
107 ??

111 = 3*37
with 3 rem is 2
and with 37 it is 33
3k+2 = 37m + 33
gives 107
@veertamizhan said:
@scrabbler no I don't have OA(?)the answer is 125 saar.
Getting 130 actually. See attached. Miscalculated last time. 125 to nahin aa raha hai kisi bhi angle se :(

regards
scrabbler

@amresh_maverick said:
107 ??111 = 3*37with 3 rem is 2and with 37 it is 333k+2 = 37m + 33gives 107
hw did u get 33 as rem wid 37?
@viewpt said:
Q: 107^109^101 div 111 R?
E(111)=36

109^101 mod 36
=(108+1)^101 mod 36
=1 mod 36

=> 107^109^101 mod 111
=107^1 mod 111