Official Quant thread for CAT 2013

@grkkrg said:
distribute 10 carrots in 2 bags => (10 + 2 - 1)C(2 -1) = 11distribute 6 radishes in 2 bags => (6 + 2 - 1)C(2 - 1) = 7total = 11 * 7 = 77But the red bag is empty in one case and the green bag in another.So 77 - 2 = 75
a+b=16 walla funda q wrong hai idhar?? 😲
@grkkrg said:
Petya's mother sends him to the market with a red and a green bag to buy 10 carrots and 6 radishes.On his way home, Petya distributes the vegetables into 2 bags in such a way that no bag is empty. In how many ways can he do this?
75.

Use formula for DIVISION OF IDENTICAL OBJECTS INTO GROUPS

(n+r-1) C (r-1) for raddishes n carrots seperately n multiply them...

11*7=77

Remove 2 cases in which either of the bag is empty... 77-2=75.

@Brooklyn said:
a+b=16 walla funda q wrong hai idhar??
16 should be identical
here 10 and 6 are not identical :)
A coin with diameter 1 cm rolls around the outside of a regular hexagon with edges of length 1 cm until it returns to its original position. In centimeters, what is the length of the path traced out by the centre of the coin?

(1) 6 +pi/2
(2) 12 + pi
(3) 6 + pi
(4) 12 + 2pi
(5) 6 + 2pi
1. Given a set A={1,2,3,4,5} B= {a,b,c} f:A->B
Find the :

a. Total Number of functions
b. Number of Surjective functions
c. Number of into functions
d. Number of bijective functions
e. Number of injective functions

Any idea how to do this ??
@nick_baba said:
A coin with diameter 1 cm rolls around the outside of a regular hexagon with edges of length 1 cm until it returns to its original position. In centimeters, what is the length of the path traced out by the centre of the coin?(1) 6 +pi/2(2) 12 + pi (3) 6 + pi (4) 12 + 2pi (5) 6 + 2pi
3) 6 + pi


r = 0.5
s = 1

path traced = perimeter of hexagon + 6 * 60/360 * 0.5 * 2pi
= 6 + pi
@nick_baba 3?
Let f(f(x)) = 2f(x) €“ x for all real x. If f(f(f(f(f(f(7)))))) = 0 then f(7) = ??
@nick_baba options?
@nick_baba said:
Let f(f(x)) = 2f(x) €“ x for all real x. If f(f(f(f(f(f(7)))))) = 0 then f(7) = ??
are you sure you didn't miss an f ? :D
@grkkrg said:
3) 6 + pir = 0.5s = 1path traced = perimeter of hexagon + 6 * 60/360 * 0.5 * 2pi= 6 + pi
can u explain ??
@grkkrg said:
3) 6 + pir = 0.5s = 1path traced = perimeter of hexagon + 6 * 60/360 * 0.5 * 2pi= 6 + pi
@audiq7 said:
@nick_baba 3?
...nopes ..OA is something else..though m not satisfied with it..wats ur take @audiq7 ??
@gautham87 said:
1. Given a set A={1,2,3,4,5} B= {a,b,c} f:A->BFind the :a. Total Number of functionsb. Number of Surjective functions c. Number of into functionsd. Number of bijective functionse. Number of injective functionsAny idea how to do this ??
Total Number of functions = 3^5

Number of Surjective functions = E(r=1 to n)(-1)^(n-r) *C(n,r)*r^m
=(-1)^2*3c1*1^5+(-1)^1*3c2*2^5+(-1)^0*3c3*3^5
=3 - 96 + 243
=150

Number of into functions = total - onto = 3^5-150 = 97

Number of bijective functions = 0

Number of injective function = 0
@nick_baba said:
Let f(f(x)) = 2f(x) €“ x for all real x. If f(f(f(f(f(f(7)))))) = 0 then f(7) = ??
f(7) = 9??
@grkkrg said:
are you sure you didn't miss an f ?
ya even i was thinking f it when i was typing this..but m pretty sure...drained lots of energy though..
@Brooklyn said:
can u explain ??
The path traced will run parallel to the sides of the hexagon at a distance of 0.5
The centre covers an arc of 60 degrees to change the direction of the path at every vertex of the hexagon.


@nick_baba said:
Let f(f(x)) = 2f(x) €“ x for all real x. If f(f(f(f(f(f(7)))))) = 0 then f(7) = ??
EDIT
(31/32)*7 ?
@ScareCrow28 said:
f(7) = 9??
nai bhai...
@nick_baba said:
Let f(f(x)) = 2f(x) €“ x for all real x. If f(f(f(f(f(f(7)))))) = 0 then f(7) = ??
7/2?
@krum
@krum said:
Total Number of functions = 3^5Number of Surjective functions = E(r=1 to n)(-1)^(n-r) *C(n,r)*r^m=(-1)^2*3c1*1^5+(-1)^1*3c2*2^5+(-1)^0*3c3*3^5=3 - 96 + 243=150Number of into functions = total - onto = 3^5-150 = 97Number of bijective functions = 0Number of injective function = 0

Thanks so much sir. But could you please explain the concept behind this ?
I'm sorry if its really basic.. but I couldn't find solutions to this or concept explanation anywhere 😞
Also, pls explain what are the conditions in which such functions exist / don't exist