Official Quant thread for CAT 2013

MBA CAT 2024
29546
@scrabbler said:
A and B...trying orally.regardsscrabbler
19
20 OA gives x+y /cos theta .
29547

@albiesriram said:
19 20 OA gives x+y /cos theta .
Oops yes, adjacent side hai not opposite :splat: My bad.

regards
scrabbler
29548

In how many ways can 10 identical presents b distributed among 6 children so tht each gets atleast one present


15C5
16C6
9C5
6^10
NOT

Please share the detail approach
29549
@abhi_14 said:
In how many ways can 10 identical presents b distributed among 6 children so tht each gets atleast one present15C516C69C56^10NOTPlease share the detail approach
solution of x1 + x2 + ... x6 = 10 such that all are greater tan 1... so 9C5
29550
@abhi_14 said:
In how many ways can 10 identical presents b distributed among 6 children so tht each gets atleast one present15C516C69C56^10NOTPlease share the detail approach
Natural number solutions of
x1+x2+x3+x4+x5+x6=10
is C(10-1,6-1)=C(9,5) ?
29551

Can some body mail me Latest No. system and Geometry by Total Gadha on my email id: [email protected]

29552
@pratskool said:
solution of x1 + x2 + ... x6 = 10 such that all are greater tan 1... so 9C5

@Buck.up
yr do we alwaz follow this approach while solving such question....I am actually confused coz I came across a question which ask us to find the no f ways to arrange 18 identical balls in 3 identical basket and there we applied the principle f counting, However wen I tried the same in the above questn i gt a wrong ans


29553
@abhi_14 said:
@Buck.up yr do we alwaz follow this approach while solving such question....I am actually confused coz I came across a question which ask us to find the no f ways to arrange 18 identical balls in 3 identical basket and there we applied the principle f counting, However wen I tried the same in the above questn i gt a wrong ans
This is where it is different....in the other question you were distributing to 6 children i.e. 6 distinct groups...here they are identical so it becomes tougher.

regards
scrabbler
29554
The half-life of a substance is 1 hr, i.e. at the end of 1 hr, its quantity reduces to one-half of what it was at the beginning of the hour. In how many hours will the quantity become less than 1% of the initial quantity?
29555
@abhi_14 Answer is 6^4

First give one to each of the children.
Then the remaining four can be given to each of the six..like 1st one to any of the 6 2nd one to any of the 6 and so on...
29556
@albiesriram said:
Q 19 n 20
19. 2/3

x*y/2 = (1 - x)*y
x = 2/3

20. (x + y)/cos(theta) ?

2y = 2x + 2z
z = y - x
y - x + 2x = y + x----> length of the base of rt angle triangle
cos(theta) = (x + y)/(length of the diagonal)
length of the diagonal = (x + y)/cos(theta)
29557
@shattereddream said:
The half-life of a substance is 1 hr, i.e. at the end of 1 hr, its quantity reduces to one-half of what it was at the beginning of the hour. In how many hours will the quantity become less than 1% of the initial quantity?
1/128
29558
@abhi_14 said:
@Buck.up yr do we alwaz follow this approach while solving such question....I am actually confused coz I came across a question which ask us to find the no f ways to arrange 18 identical balls in 3 identical basket and there we applied the principle f counting, However wen I tried the same in the above questn i gt a wrong ans
Please post that ques if you have and its OA.
29559
@shattereddream said:
The half-life of a substance is 1 hr, i.e. at the end of 1 hr, its quantity reduces to one-half of what it was at the beginning of the hour. In how many hours will the quantity become less than 1% of the initial quantity?
7 I guess...? 1/128 ho jayega.

Or else can do like this as well, bit longer:

0.5
0.25
0.125
0.0625
0.03125
0.015625
0.0078125

regards
scrabbler
29560
@shattereddream said:
The half-life of a substance is 1 hr, i.e. at the end of 1 hr, its quantity reduces to one-half of what it was at the beginning of the hour. In how many hours will the quantity become less than 1% of the initial quantity?
Concentration
C

So 7 hours..?
29561
@scrabbler could u pls share the approach to tackle all the four cases i.e.:
1. identical balls, identical basket
2.identical balls, different basket
3.different basket, identical ball
4.different basket, different ball

or if u knw any good source fr this funda, could u pls share this, I hv lot f confusion related to this topic

PS: Ur blog seems to b really good, great initiative
29562
@messidbarca said:
@abhi_14 Answer is 6^4First give one to each of the children.Then the remaining four can be given to each of the six..like 1st one to any of the 6 2nd one to any of the 6 and so on...
You are assuming the other 4 to be distinct....they are also identical. So if you want to do it this way you have to do n+r-1Cr-1 i.e 4+5C5 which again gives the same 9C5 = 126 ways.

regards
scrabbler
29563
@shattereddream said:
The half-life of a substance is 1 hr, i.e. at the end of 1 hr, its quantity reduces to one-half of what it was at the beginning of the hour. In how many hours will the quantity become less than 1% of the initial quantity?
after 7 hrs ?

1....100
2....50
3....25
4....12.5
5....6.25
6....3.125
7....1.5625
8....0.78xxx
29564
@messidbarca said:
@abhi_14 Answer is 6^4First give one to each of the children.Then the remaining four can be given to each of the six..like 1st one to any of the 6 2nd one to any of the 6 and so on...
The OA is 9C5 ,as mentioned by puys above....
29565
@shattereddream is it 7 dude..