Official Quant thread for CAT 2013

@viewpt said:
Q: in how many ways one can paint all the sides of a hexagon?
neither clarity hai Q mein..kitne colors and all..nor options
@jain4444 said:
number of squares ?
16
@viewpt said:
Q: in how many ways one can paint all the sides of a hexagon?
all same->1 way
5 same , 1 diff ->6c1 * 2!
4 same ,2 diff -> 6c2*3!
4 same 2 same ->6c2*2!

3same 3 same ->6c3 * 2!
3 same 2 same 1 dif -> 6c3*3c2*3!
3 same 3 diff -> 6c3*4!

add all above?
@jain4444 said:
all correct@viewpt pranam bhai With the use of three different weights, namely, 1gm, 3gm , 9gm and 27gm . In how many ways different weights can be weighed, if the objects to be weighed and the given weights may be placed in either pan of the scale ? (both pans are not identical)
both pans are nt identical means ?
...will update here....
@jain4444 said:
all correct@viewpt pranam bhai With the use of three different weights, namely, 1gm, 3gm , 9gm and 27gm . In how many ways different weights can be weighed, if the objects to be weighed and the given weights may be placed in either pan of the scale ? (both pans are not identical)
3 powers soo

1+3+9+27 = 40 so all upto 40 ?

wt does this both pans nt identical mean?? 😲
@viewpt said:
Q: in how many ways one can paint all the sides of a regular hexagon?
All sides can only be painted in 1 way, rather question should be "In how many ways one can paint the sides of a regular hexagon?"

Then answer would be 12, considering symmetry.

For painting 1 side - 1way

2-3Ways

3-3Ways

4-3Ways

5-1Ways

6-1Ways
@Brooklyn said:
3 powers soo1+3+9+27 = 40 so all upto 40 ?
here non identical is given, confusion go rahi hai
@sujamait said:
both pans are nt identical means ?...will update here....
@Brooklyn said:
3 powers soo1+3+9+27 = 40 so all upto 40 ?wt does this both pans nt identical mean??

ek red color ka hai aur ek green
@jain4444
if you mean 'different ways of weighing' then it should be 40x2 = 80
@jain4444 said:
all correct@viewpt pranam bhai With the use of three different weights, namely, 1gm, 3gm , 9gm and 27gm . In how many ways different weights can be weighed, if the objects to be weighed and the given weights may be placed in either pan of the scale ? (both pans are not identical)
40 tak kar sakte h.
3 ki power ki series h
to jo measure ho sakta h wo in sab ka sum hota h 1+3+9+27=40
ab ques k according 40 *2 =80 ways h answer
Tell me if i am wrong 😃
@jain4444 said:
all correct@viewpt pranam bhai With the use of three different weights, namely, 1gm, 3gm , 9gm and 27gm . In how many ways different weights can be weighed, if the objects to be weighed and the given weights may be placed in either pan of the scale ? (both pans are not identical)
Another way of doing. Which is actually the same as the one mentioned by you a couple of pages earlier.
Every weight can be placed in 3 ways (Left pan/Right Pan/No Pan)
So total ways
= 3x3x3x3 -1 [Minus 1 for the case that no wieght is placed in any pan]
= 80
@sujamait said:
both pans are nt identical means ?...will update here....
I guess it means that we can go from 40 to -40 i.e. 81 possibilities for the difference between the pans...but the number of distinct weights we could weigh would be 1 till 40 only.

Or another way to look at it is, we can put each weight in either pan or in neither so each of the weight has 3 possibilities so for 4 weights we have 3^4 = 81 possibilities (since the weights are powers of 3, there is no way any two can add up to give a third so there will be no overlaps)

regards
scrabbler

@scrabbler said:
I guess it means that we can go from 40 to -40 i.e. 81 possibilities for the difference between the pans...but the number of distinct weights we could weigh would be 1 till 40 only.Or another way to look at it is, we can put each weight in either pan or in neither so each of the weight has 3 possibilities so for 4 weights we have 3^4 = 81 possibilities (since the weights are powers of 3, there is no way any two can add up to give a third so there will be no overlaps)regardsscrabbler
makes sense: -40 to 40=> 81

@jain4444 ans de do
@scrabbler said:
I guess it means that we can go from 40 to -40 i.e. 81 possibilities for the difference between the pans...but the number of distinct weights we could weigh would be 1 till 40 only.Or another way to look at it is, we can put each weight in either pan or in neither so each of the weight has 3 possibilities so for 4 weights we have 3^4 = 81 possibilities (since the weights are powers of 3, there is no way any two can add up to give a third so there will be no overlaps)regardsscrabbler
ohk..yeah realized Q asks for "In how many ways different weights can be weighed"

@viewpt said:
3^4=81hence till 80 then two diff pans toh 80*2=160 whr gettting wrong??
3^4 is when you are considering the two pans.

For every weight you have three possibilities
i) It is not used
ii) It is on Pan 1
iii) It is on Pan 2

Now, there are 4 weights, so 3^4 ways (but we need to remove the case when none of the weight is chosen)

So, 3^4 - 1 = 80 ways
Let N be the smallest positive integer with six positive odd integer divisors and twelve positive even integer divisors. Find the sum of the digits of N?
OPTIONS

1) 18
2) 9
3) 27
4) 15

Let the roots of x^3 + 3x^2 + 4x – 11 = 0 be a, b, c and the roots of x^3 + rx^2 + sx + t = 0 are a + b, b + c, c + a the find the value of t?
OPTIONS

1) 0
2) –11
3) 23
4) 98


thak gaye :|
@sujamait said:
Let N be the smallest positive integer with six positive odd integer divisors and twelve positive even integer divisors. Find the sum of the digits of N?OPTIONS1) 18 2) 9 3) 27 4) 15
9?

The number will be 180 I think...2^2 x 3^2 x 5^1

regards
scrabbler

@sujamait said:
Let N be the smallest positive integer with six positive odd integer divisors and twelve positive even integer divisors. Find the sum of the digits of N?OPTIONS1) 18 2) 9 3) 27 4) 15
Total factors=18=2 * 3^2
(1+1)(2+1)(2+1)
Smallest will be 2^2*3^2*5=180
Sum 9
?
@sujamait said:
Let the roots of x^3 + 3x^2 + 4x €“ 11 = 0 be a, b, c and the roots of x^3 + rx^2 + sx + t = 0 are a + b, b + c, c + a the find the value of t?OPTIONS1) 0 2) €“11 3) 23 4) 98 thak gaye
23?
@sujamait said:
Let the roots of x^3 + 3x^2 + 4x €“ 11 = 0 be a, b, c and the roots of x^3 + rx^2 + sx + t = 0 are a + b, b + c, c + a the find the value of t?OPTIONS1) 0 2) €“11 3) 23 4) 98 thak gaye
23 aa raha hai...just rechecking....

regards
scrabbler