Official Quant thread for CAT 2013

the answer sheet of 5 eng students can be checked by one of the 9 prof what is the probability that all the 5 answwer sheets are checked by exactly two professors

P is a prime number greater than 37. Then the largest number that will always divide (P-1)(P+1) is ______

@arumugadas said:
the answer sheet of 5 eng students can be checked by one of the 9 prof what is the probability that all the 5 answwer sheets are checked by exactly two professors
36*2^5/9^5
?
@kingsleyx said:
P is a prime number greater than 37. Then the largest number that will always divide (P-1)(P+1) is ______
12 ?
@kingsleyx said:
P is a prime number greater than 37. Then the largest number that will always divide (P-1)(P+1) is ______
24?
@kingsleyx 24 ayega
41 take prime number
40*42=1680
divide by 24 we get 70
42*44=1848
divide by 24 we get 77
46*48/24=92
and so on............
@maddy2807 40/2187
Let n be a 5-digit number, and let q and r be the quotient and remainder, respectively, when n is divided by 100. For how many values of n is q + r divisible by 11?
@arumugadas it should be 5!/9^4
:P i dont know how but according to ur answere this situation fits
@sauravd2001 said:
@arumugadas it should be 5!/9^4 i dont know how but according to ur answere this situation fits
i personally feel it cant be this way..
@jain4444 said:
Let n be a 5-digit number, and let q and r be the quotient and remainder, respectively, when n is divided by 100. For how many values of n is q + r divisible by 11?
n = 100q + r = 99q + (q + r)

n mod 11 = (q + r) mod 11 => If (q + r) is divisible by 11, then n is also divisible by 11

-> All 5 digits numbers which are divisible by 11 => 8181 ?
@arumugadas said:
the answer sheet of 5 eng students can be checked by one of the 9 prof what is the probability that all the 5 answwer sheets are checked by exactly two professors
jain bhai throw some light on this
@jain4444

sir logic i thnk to this problem:

q can range b/w 100 to 9999
r can range b/w 0 to 99

now to get q+r divisble by 11

we need either both q = r=11k type

or (11K+5, 11+6), (11K+2, 11K+9) so on??
@kingsleyx said:
P is a prime number greater than 37. Then the largest number that will always divide (P-1)(P+1) is ______
In any case factors will be (2^3*3)2^x*3*y...
24?
@arumugadas said:
the answer sheet of 5 eng students can be checked by one of the 9 prof what is the probability that all the 5 answwer sheets are checked by exactly two professors
@maddy2807 said:
36*2^5/9^5?
9c2*30/ (9c1*1 + 9c2*30 + 9c3*150 + 9c4*240 + 9c5*120)

= 40/2187

http://www.pagalguy.com/posts/4105695
@kingsleyx said:
P is a prime number greater than 37. Then the largest number that will always divide (P-1)(P+1) is ______
dude OA ??
@jain4444 bhai 8181 because every 100 has 9 such pairs
900 pairs of 100 so
8100
and see this 990=110+(n-1)*11
n=81
so
8100+81=8181
@jain4444 81*100+81=8181
@jain4444 said:
Let n be a 5-digit number, and let q and r be the quotient and remainder, respectively, when n is divided by 100. For how many values of n is q + r divisible by 11?
5 digit multiples of 11 = 10010 - 99990 => 8181


@krum said:
5 digit multiples of 11 = 10010 - 99990 => 8181
yar question is : q+r to be divisible by 11 !! not n