Official Quant thread for CAT 2013

@vijay_chandola said:
Is integer N a prime number?I. N = p! + 1 for some prime number pII. q! + 1 a) if the question can be answered using statement I alone but not using II aloneb) if the question can be answered using statement II alone but not using I alonec) if the question can be answered using either statement aloned) if the question can be answered using statements I and II together but not using eitheralonee) if the question cannot be answered even by using both statements I and II together
1. N = 5! + 1 = Not a Prime
2. 2! + 1

So c)
@vijay_chandola said:
Is integer N a prime number?I. N = p! + 1 for some prime number pII. q! + 1 a) if the question can be answered using statement I alone but not using II aloneb) if the question can be answered using statement II alone but not using I alonec) if the question can be answered using either statement aloned) if the question can be answered using statements I and II together but not using eitheralonee) if the question cannot be answered even by using both statements I and II together
statement 1 5!+1=121 not a prime no. and 3!+1=7 prime no. so nothing can be said,
statement 2 well n>q!+1 so it can be q!+2mod2=0, q!+3mod3=0.....q!+(q-1)modq-1=0 so it cannot be prime no. so from statement b alone we can answer however nothing can be said by 1st statement. so optB

a + b = 2p

ab = p^2 - 1
so roots p+1 , p-1

p is integer ? aese toh p kitni he values lega
@krum said:
Consider the following quadratic equation: The roots of this equation lie in the interval ( €“4, 5). Find the sum of [p] where p takes all its possible values.[x] indicates the Greatest Integer Function less than or equal to x.OPTIONS1) 0 2) 4 3) 5 4) None of these
@Shray14 said:
30??
@rkshtsurana said:
a + b = 2pab = p^2 - 1so roots p+1 , p-1p is integer ? aese toh p kitni he values lega
age try kar, aa jaega ,sara data use kar
@sowmyanarayanan said:
1. N = 5! + 1 = Not a Prime 2. 2! + 1 So c)
So b)
How careless :P
@Shray14 said:
According to the survey, the population of a city increase by 10% every year for two years and then decreases by 10% every year for two years. If population just before 4 years was 100000, what was it after four years? 108900980109610092400980100
is it 96100?
@pussu01 said:
is it 96100?
980100
@krum said:
age try kar, aa jaega ,sara data use kar
Mein bhi p+1 and p-1 par attak agay..bro agae soltn??
and phele wale question ka bhi..
1).
P(17) = a.(17)^2 + b.(17) + c = 10
P(24) = a.(24)^2 + b.(24) + c = 17

Subtracting 1st equation from the second one, we get
41a + b = 1
=> the two ordered pair of solutions for (a,b) are (-1, 42) and (1, -40)

Now, P(n) = a.n^2 + b.n + c = n + 3
=> a.n^2 + (b-1)n + c - 3 = 0

We require n1 + n2, which is the sum of roots = - (b-1)/a
We get the value as 41 as the unique answer.


2).
x2 − 2px − 1 + p2 = 0

x2 − 2px + p2 − 1 = 0

∴ (xp)2 − 1 = 0

∴ (xp + 1)(xp − 1) = 0
So, the roots of the equation are (p – 1) and (p + 1), both of which lie in the interval (–4, 5).

Case 1:

p– 1 > –4, and p + 1 =>p > –3, and p =>–3 p
When –3 p p] = –3;
When –2 ≤ p p] = –2;
When –1 ≤ p p] = –1;
When 0 ≤ p p] = 0;
When 1 ≤ p p] = 1;
When 2 ≤ p p] = 2;
When 3 ≤ p p] = 3;

Thus, the sum of [p] is 0, as p assumes values in –3 p

similarly for case 2

so sum=0

@rkshtsurana , @Shray14
OA of the previous question:
Using statement I alone, N may or may not be prime, e.g. 3! + 1 = 7 (prime), 5! + 1 = 121 (not prime) Using statement II alone, N can be equal to q! + 2 or q! + 3 or €Ś q! + q which are divisible by 2, 3, €Ś q respectively. So, N cannot be prime. Hence, [2].
A Question to be answered::

What is the 2037th positive integer that can be expressed as the sum of two or more consecutive positive integers? (The first three are 3 = 1+2, 5 = 2+3, and 6 = 1+2+3.)

No OA...Please discuss in details.

(Edited) Is the answer 2049 ???
@staaalinnn said:
A Question to be answered::What is the 2037th positive integer that can be expressed as the sum of two or more consecutive positive integers? (The first three are 3 = 1+2, 5 = 2+3, and 6 = 1+2+3.)No OA...Please discuss in details. (Edited) Is the answer 2049 ???
all numbers except for powers of 2

upto 2037th term, 2^0-2^10 - 11 numbers
taking next 11 numbers we get 2037+11=2048
but 2048=2^11
=>2049
@krum said:
all numbers except for powers of 2upto 2037th term, 2^0-2^10 - 11 numberstaking next 11 numbers we get 2037+11=2048but 2048=2^11=>2049
That means my answer was correct too... yippie
@krum bth d ques are nyc..1st hgya tha..2nd one..cnfuse hgya.. aur laa aese ques
@staaalinnn said:
A Question to be answered::What is the 2037th positive integer that can be expressed as the sum of two or more consecutive positive integers? (The first three are 3 = 1+2, 5 = 2+3, and 6 = 1+2+3.)No OA...Please discuss in details. (Edited) Is the answer 2049 ???
we have to exclude 1,2,8,16,.....1024=11 numbers
==> 2037+11=2048+1=2049
Consider the increasing sequence - 1, 3, 4, 9, 10, 12, 13 €Ś and so on. The sequence consists of all those positive integers which are powers of 3 or sum of distinct powers of 3.

Find the 100th term of the sequence.
OPTIONS

1) 978
2) 981
3) 932
4) 987
5) None of these

Q> How many ordered triples of three positive integers (a, b, c) exist such that a続 + b続 + c続 = 2011? OA again..

@vijay_chandola , @krum and @Brooklyn bhai..please help on this ~~~
@staaalinnn said:
A Question to be answered::What is the 2037th positive integer that can be expressed as the sum of two or more consecutive positive integers? (The first three are 3 = 1+2, 5 = 2+3, and 6 = 1+2+3.)No OA...Please discuss in details. (Edited) Is the answer 2049 ???
basically the numbers that dont have any odd factors cant be expressed as a sum of 2 or more consecutive no.s so you have exclude only powers of 2.
and so you will need to subtract upto 2^11 so actually 12 numbers so 2037th terms must be 2037+12=2049
Is |x 창€“ 3| I. |x| > 2
II. |x 창€“ 1|


a) if the question can be answered using statement I alone but not using II alone
b) if the question can be answered using statement II alone but not using I alone
c) if the question can be answered using either statement alone
d) if the question can be answered using statements I and II together but not using either
alone
e) if the question cannot be answered even by using both statements I and II together

@krum : :thumbsup: for the second question's solution :D
XAT mai hi possible h iska aana :splat:
@staaalinnn said:
Q> How many ordered triples of three positive integers (a, b, c) exist such that a続 + b続 + c続 = 2011? OA again..
no solution
cubes are form 9k , 9k+1, 9k-1
2011/ 9 rem 4
and by no means we can sub 4 or add 5