Official Quant thread for CAT 2013

MBA CAT 2024
22407
@jain4444 said:
In a class of 100 students 70 passed in physics, 62 passed in mathematics, 84 passed in english and 82 passed in chemistry. 37 students passed in all 4 subjects. How many maximum students could have failed all four subjects?(a) 12 (b) 17 (c) can not be determined (d) none of the foregoing
Option d
22408
@ani6 said:
PLZ HELP....In how many ways 10 identical presents can be distributed among 6 children ,so that each child gets atleast one present.(a) C(15,5) (b) C(16,6) (c) C(9,5) (d) 6^10Ans : (c) C(9,5)
a + b + c + d + e + f = 10

no. of ways = (10 - 1)c(6 - 1) = 9c5
22409
@ani6 said:
PLZ HELP....In how many ways 10 identical presents can be distributed among 6 children ,so that each child gets atleast one present.(a) C(15,5) (b) C(16,6) (c) C(9,5) (d) 6^10Ans : (c) C(9,5)
a+b+c+d+e+f = 10
now give 1 to all , as each should have one atleast
so,
a+b+c+d+e+f = 4
so,
9c5
22410
@jain4444 said:
In a class of 100 students 70 passed in physics, 62 passed in mathematics, 84 passed in english and 82 passed in chemistry. 37 students passed in all 4 subjects. How many maximum students could have failed all four subjects?(a) 12 (b) 17 (c) can not be determined (d) none of the foregoing
i m getting the answer as 16.. is it right?
22411
@ChirpiBird said:
13
see.. 67-37 = 25 students are passing in 1,2 or 3 (physics included)
aise hi ...
70-37.. 33, and 82-37=45 and 84-37 =47.
totl =150.
150students aise hain jo either 1 ya 2 ya 3 mein pass hain.
ab fail ko maximize karne k liye , pass ko minimize karoge...lets say none passed in jus 1 or jus 2 subjs.


also, 1 student max 3 subj mein paas ho sakta h..
so 150/3 ... 50 students aise hain jo all 3 subjects mein paas h.

ab 37 aise hain jo 4 mein paas h.

so 50+37.. 87.(pass)

total 100.
100-87=13

P.S : eng/hindi pe dhyan na de, #RIPeng_and_hindi
22412
@ChirpiBird said:
see.. 67-37 = 25 students are passing in 1,2 or 3 (physics included)aise hi ... 70-37.. 33, and 82-37=45 and 84-37 =47.totl =150. 150students aise hain jo either 1 ya 2 ya 3 mein pass hain.ab fail ko maximize karne k liye , pass ko minimize karoge...lets say none passed in jus 1 or jus 2 subjs.also, 1 student max 3 subj mein paas ho sakta h.. so 150/3 ... 50 students aise hain jo all 3 subjects mein paas h.ab 37 aise hain jo 4 mein paas h.so 50+37.. 87.(pass)total 100. 100-87=13P.S : eng/hindi pe dhyan na de, #RIPeng_and_hindi
Hmm..
but I think kuch gard bard hai...
what i did was checked the subject in which maximum number of students passed..
I think kissi mein 84 hai...
So 16 students have failed in this subect...
similarly for the rest took out the number of failing students in a particular subject..
so 16 was the minimum number who have failed in a particular subject,
hence if these 16 failed in all others (as 16 is the minimum..baaki number esse bade hain) so
all subject failing ka toh 16 aata hai....
do not know kisne galti hai??
22413

time n work

Q. It takes bhuvan , bheem n bahadur 18,24 n 36 days to do a piece of work . each of them does the same amt of wrk n they complete the wrk in 26 days . instead if bheem did xtra wrk equal to the sum of y th parts of the wrks done by bhavan n bahadur , they cld hav completd the wrk 1 day earlier . hw much more wrk did bheem do in the second case as compared to tht done by him in the first case ??

options a)1/9 b) 1/6 c) 1/4 d) 1/3

need soln plz
22414
@saurav205 said:
Hmm..but I think kuch gard bard hai...what i did was checked the subject in which maximum number of students passed..I think kissi mein 84 hai...So 16 students have failed in this subect...similarly for the rest took out the number of failing students in a particular subject..so 16 was the minimum number who have failed in a particular subject,hence if these 16 failed in all others (as 16 is the minimum..baaki number esse bade hain) soall subject failing ka toh 16 aata hai....do not know kisne galti hai??


true.
see i found the same answer considering failures too.
37 passed in all.
which means 63 failed in atleast one.
max 3 subjs mein fail ho sakte hain.. 63/3 = 21
also... like u found 16 failed in one of the subj, aise hi find for others..
30,38,16,18 .. total = 102 students failed in atleast one.
again same logic max ko 3 subj mein fail karvao... 102/3 = 34

34-21= 13 failed in all 4.

dont know.. some QA guru explain..
22415
@saurav205 said:
Hmm..but I think kuch gard bard hai...what i did was checked the subject in which maximum number of students passed..I think kissi mein 84 hai...So 16 students have failed in this subect...similarly for the rest took out the number of failing students in a particular subject..so 16 was the minimum number who have failed in a particular subject,hence if these 16 failed in all others (as 16 is the minimum..baaki number esse bade hain) soall subject failing ka toh 16 aata hai....do not know kisne galti hai??


true.
see i found the same answer considering failures too.
37 passed in all.
which means 63 failed in atleast one.
max 3 subjs mein fail ho sakte hain.. 63/3 = 21
also... like u found 16 failed in one of the subj, aise hi find for others..
30,38,16,18 .. total = 102 students failed in atleast one.
again same logic max ko 3 subj mein fail karvao... 102/3 = 34

34-21= 13 failed in all 4.

dont know.. some QA guru explain..
22416
@jain4444 said:
In a class of 100 students 70 passed in physics, 62 passed in mathematics, 84 passed in english and 82 passed in chemistry. 37 students passed in all 4 subjects. How many maximum students could have failed all four subjects?(a) 12 (b) 17 (c) can not be determined (d) none of the foregoing
Sir jee OA kya hai eska??
If its none of these , then please can you provide the answer..as in what it should be...
There has been a lot of discussion over this...people are getting D..but then the final answer is not matching....
22417
@ChirpiBird said:

true. see i found the same answer considering failures too. 37 passed in all. which means 63 failed in atleast one.max 3 subjs mein fail ho sakte hain.. 63/3 = 21 also... like u found 16 failed in one of the subj, aise hi find for others..30,38,16,18 .. total = 102 students failed in atleast one.again same logic max ko 3 subj mein fail karvao... 102/3 = 3434-21= 13 failed in all 4.
I agree with 13, but mera logic aur bhi complicated ho gaya...:(

regards
scrabbler
22418

sum of lcm and hcf of 121212 and 777777

1: 848373
2: 848596
3: none of.the abobe
4: 848484848484
22419
@jain4444 said:
In a class of 100 students 70 passed in physics, 62 passed in mathematics, 84 passed in english and 82 passed in chemistry. 37 students passed in all 4 subjects. How many maximum students could have failed all four subjects?(a) 12 (b) 17 (c) can not be determined (d) none of the foregoing
i am getting 13...
22420
@jain4444 said:
In a class of 100 students 70 passed in physics, 62 passed in mathematics, 84 passed in english and 82 passed in chemistry. 37 students passed in all 4 subjects. How many maximum students could have failed all four subjects?(a) 12 (b) 17 (c) can not be determined (d) none of the foregoing
It is coming out to be 13. :splat:
22421
@scrabbler said:
I agree with 13, but mera logic aur bhi complicated ho gaya...regardsscrabbler
explain kar do plz... right now even i am at sea.
22422
@ChirpiBird said:
see.. 67-37 = 25 students are passing in 1,2 or 3 (physics included)aise hi ... 70-37.. 33, and 82-37=45 and 84-37 =47.totl =150. 150students aise hain jo either 1 ya 2 ya 3 mein pass hain.ab fail ko maximize karne k liye , pass ko minimize karoge...lets say none passed in jus 1 or jus 2 subjs.also, 1 student max 3 subj mein paas ho sakta h.. so 150/3 ... 50 students aise hain jo all 3 subjects mein paas h.ab 37 aise hain jo 4 mein paas h.so 50+37.. 87.(pass)total 100. 100-87=13P.S : eng/hindi pe dhyan na de, #RIPeng_and_hindi
the mistake you are doing is you are not following venn diagram ka rule.. for 4 set venn you have
I+II+III+IV=100
I+2II+3III+4IV=298
PUT IV=37
I+2II+3III=150
SUBTRACT FROM FIRST EQUATION
II+2III=83
III(MAX)=41 and not 50 as you got
22423
@Estallar12 said:
It is coming out to be 13.
@ChirpiBird said:
explain kar do plz... right now even i am at sea.
Here the Total = 70 + 62 + 84 + 82 = 298.

All four subjects = 37
So, 4*37 = 148 students.

Now, Left Out will be = 298 - 148 = 150 students.

These 150 will have passed in 1 only OR 2 only or 3 only.

So, Sum taking into consideration their contribution too
=> x + 2y + 3z = 150
So, z = 50 when x = y = 0 satisfies.

Thus, 50+37 = 87 done.

=> Rest 13 failed. :splat:
22424
@iLoveTorres said:
the mistake you are doing is you are not following venn diagram ka rule.. for 4 set venn you haveI+II+III+IV=100I+2II+3III+4IV=298PUT IV=37"I+2II+3III=150"SUBTRACT FROM FIRST EQUATIONII+2III=83III(MAX)=41 and not 50 as you got
bold part mein I, 2II zero ho jaye toh III 50 hi toh hoga..

this i mentioned na.. "lets say none passed in jus 1 or jus 2 subjs."
22425
@DespicableA said:
sum of lcm and hcf of 121212 and 7777771: 8483732: 8485963: none of.the abobe4: 848484848484
121212 = 2^2*3^2*7*13*37
777777 = 3*7^2*11*13*37

LCM = 2^2*3^2*7^2*11*13*37
HCF = 3*7*13*37

LCM's units digit = 4*9*9*1*3*7 = xxx4
HCF's units digit = 1*3*7 = xxx1

hence, LCM+HCF's units digit = xxxx5

so None of these??
22426
@ChirpiBird said:
bold part mein I, 2II zero ho jaye toh III 50 hi toh hoga..this i mentioned na.. "lets say none passed in jus 1 or jus 2 subjs."
maths assumption pe chale toh iska answer should be 0 failed in all the four.. fail hona kisse pasand hai.. min and max ko rule ke hisab se solve karte hai na? jus like that you can decide the maximum value for a variable.. agree?