Official Quant thread for CAT 2013

@Dexian
I know the answer. Please let me know the logic u followed.
@jain4444
Answer is D) 1120
@jain4444 said:
SP of shirt = x SP of coat = (4000 - x) let CP of coat = 300y CP of shirt = 175y x - 175y = 4000 - x - 300y => 2x + 125y = 4000 from option only 1 value will satisfy this i.e. 2100
if price of shirt is 2100
then price of coat is ~ 3318....

then the guy cannot have profit on 4000 coz his CP in total is 5418 and SP is 4000

@Dexian

How did you get 133?

@Shrutim90 said:
@DexianI know the answer. Please let me know the logic u followed.
eliminate from the options... and the reply above will help :)

@VJ12 said:
@DexianHow did you get 133?
took each number from 2 to 19 and counted....
not sue may be wrong...
dont know the OA...
@Shrutim90 @Dexian my bad hum LOSS same kar diye

@Swavi91

What was your approach for the co prime question?

Did you count or did you follow any other approach?

@VJ12 just counted using prime factorization & the constraints given..
@hesse said:
@The_LoserD1 + D2 +D3 +D4 = 17D represents diceFind number of ways. ?d1 d2 d3 d46 6 4 1 - 12 ways6 6 3 2 - 12 ways6 5 4 2 - 24 ways6 5 5 1 - 12 ways6 5 3 3 - 12 ways5 5 5 2 - 4 ways5 5 4 3 - 12 ways5 4 4 4 - 4 ways

Also 6 4 4 3 - 12 ways

So I get 104.

OA kya hai?

regards
scrabbler



@The_Loser said:
could you rectify this. ?a+b+c+d = 17a'+b'+c'+d' = 13now 16c3 - 4 * 10c3 = 80
How about this logic: When you do 10C3 you are removing cases when 1 die goes above 6 right? But what about the cases where 2 dice go above 6? These will be subtracted twice in the above situation...so need to be added back.

Each such case occurs 4c3 times. and there are 4C2 i.e. 6 such cases where 2 of the 4 dice cross 6. So we need to add back 4C3 * 6 = 24.

3 of the dice cannot cross 6 simultaneously ad the total is 17 only. So we can say it should be 16C3 - 4 * 10C3 + 6 * 4C3 = 104.

regards
scrabbler


@rkshtsurana
@Shrutim90 said:
@DexianI know the answer. Please let me know the logic u followed.
the approach can be
let the cost price of coat =x
cost price of shirt =58.33% of x =(50%+8.33%) of x=(1/2+1/12)x =7/12x
total cost price =x +(7/12)x =19/12x
now if the shirt's price is 2000 then
7/12 part is 2000 so obviously 19/12 parts wil be greater than 4000 and hence by sellinh the shirt and coat at 4000 there wil be a loss
oly one option is below 2000. hence D
@The_Loser said:
Triangle having perimeter = 100.all side integeral.How many triangle possible. ?
Options hai? Mera 1173 ke aaspaas aa raha hai...

regards
scrabbler

@The_Loser said:
Triangle having perimeter = 100.all side integeral.How many triangle possible. ?
Options hai? Mera 1173 ke aaspaas aa raha hai...

regards
scrabbler

How many pairs of integers (not necessarily positive) are there such that both a^2 + 6b^2 and b^2 + 6a^2 are both squares ?
@Shrutim90 said:
Selling price of a shirt and a coat is Rs. 4000. The cost price of a shirt is 58.33% of the cost price of a coat and so amount of profit on both the shirt and coat is same, then the price of the shirt could be:a) 2100b) 2525c) 2499d) 1120

58.33% = 7/12. So Price of shirt : coat is 7 : 12 and so shirt is 7/19 of total CP. Since there is a profit, total CP
regards
scrabbler

@scrabbler said:
Options hai? Mera 1173 ke aaspaas aa raha hai...regardsscrabbler
1176?sorry ab pata chala y u getting 1173..
@jain4444 said:
How many pairs of integers (not necessarily positive) are there such that both a^2 + 6b^2 and b^2 + 6a^2 are both squares ?
4?
@iLoveTorres said:
1176?sorry ab pata chala y u getting 1173..


Paper nahin hai so solved on my hand :blush: ...started with natural solutions of a + b + c = 100 and removed cases when any of the 3 became 50 or more...but I think I did whole number instead of natural solutions so kuch galat ho gaya...didn't have patience/paper to redo hence "approx" answer bola.

Edit: 1176 hi correct hai....99C2 - 3 * 50C2 = 99*49 - 3*25*49 = 24 * 49 = 1176

Dubara edit: Ab paper leke aaya :D

regards
scrabbler