Official Quant thread for CAT 2013

MBA CAT 2024
7641
@deedeedudu said:
(x-18)(y-54)=18*54=2^2*3^5(x-18)=1,3,9,274 values
7642

a, b, c, d, e, f are six positive integers such that :

b+c+d+e = 4a
c+f=3a
c+d+e=2f
f=2d
e+f=2c+1

"a" is a prime number between 12 and 20.

the value of f is_________?

7643
@gautam22 said:
sir 81 kyun nahi liya?
Missed it edited and dont call me sir yaar
7644
@Torque024 said:
@rubikmath@soham2208@gautam22First time I also got 5, but it ain't OA.
@Torque024 I don't understand, is only X less than 100, or even Y is less than 100 ? 😐

This is right => (X-18)*(Y-54) = (2^2)*(3^5)

Now, X - 18 is odd -> X - 18= 1/-1/3/-3/9/-9/27/81

So, X = 19/17/21/15/27/9/45/99
corresponding values of Y = 54*19/-ve/54*7/-ve/54*3/-ve/90/76

So, what is the flaw here ? If Y is not less than 100, there are 5 solutions, otherwise 2 ? :/
7645
@gautam22 said:
OA kya hai?

2 dia hua hai, mera bhi 5 hi aa rha.

7646
@kingsleyx said:
a, b, c, d, e, f are six positive integers such that :b+c+d+e = 4ac+f=3ac+d+e=2ff=2de+f=2c+1"a" is a prime number between 12 and 20.the value of f is_________?
28?
7647
@kingsleyx said:
a, b, c, d, e, f are six positive integers such that :b+c+d+e = 4ac+f=3ac+d+e=2ff=2de+f=2c+1"a" is a prime number between 12 and 20.the value of f is_________?
28?
7648
@kingsleyx said:
a, b, c, d, e, f are six positive integers such that :b+c+d+e = 4ac+f=3ac+d+e=2ff=2de+f=2c+1"a" is a prime number between 12 and 20.the value of f is_________?
28
7649
@kingsleyx said:
a, b, c, d, e, f are six positive integers such that :b+c+d+e = 4ac+f=3ac+d+e=2ff=2de+f=2c+1"a" is a prime number between 12 and 20.the value of f is_________?
a=17 and f= 28 ?
7650
If 'a' is one of the roots of x^5-1=0 and a not equals 1,then what is the value of a^15+a^16+a^17...+a^50?
7651
@Torque024 said:
If 'a' is one of the roots of x^5-1=0 and a not equals 1,then what is the value of a^15+a^16+a^17...+a^50?
How many times do we solve this :/ ?

http://www.pagalguy.com/forums/quantitative-ability-and-di/official-quant-thread-cat-2011-part-3-t-69715/p-2841386/r-2854151
7652
@soham2208 It was for practice

Alby, Benny, Cindy and Dan houses forms a square field ABCD. A cow, in a square field, is 13 meters from Benny's house, 17 meters from Dan's house, and 20 meters from Cindy's house. Find the area of the field. Assume house to be a point object and field to be flat.
7653
@kingsleyx said:
a, b, c, d, e, f are six positive integers such that :b+c+d+e = 4ac+f=3ac+d+e=2ff=2de+f=2c+1"a" is a prime number between 12 and 20.the value of f is_________?
28?
7654
The average weight of 8 people decreases by 2 kgs, when two new people are added to the
group. If the difference between the original weight and new weight is 36 kgs, find the new total
weight of the people.
7655
@Torque024 said:
If 'a' is one of the roots of x^5-1=0 and a not equals 1,then what is the value of a^15+a^16+a^17...+a^50?

See in case of X^3 - 1 = 0 , the roots are cube roots of unity , i.e 1,w,w^2.

In it 1+w+w^2 = 0

and w^3 = 1 is applicable.

Now coming to this case: X^5 - 1 = 0 ;

Here 5th roots of unity is there so roots : 1,w,w^2,w^3,w^4

So, 1+w+w^2+w^3+w^4 = 0

and w^5 = 1;

Let a = w ;

w^15 ( 1 + w + w^2 + w^3 + w^4) +....+ w^45 ( 1 + w + w^2 + w^3 + w^4) + w^50

= w^50

= 1

7656

Hello everyone..m stuck in ths ques..pls help ..
if a+b+c=8,then the value of (a-4)^3+(b-3)^3+(c-1)^3-3(a-4)(b-3)(c-1) is
a)2
b)4
c)1
d)0

7657
@Cat.Aspirant123 said:
The average weight of 8 people decreases by 2 kgs, when two new people are added to thegroup. If the difference between the original weight and new weight is 36 kgs, find the new totalweight of the people.
260 kg?
7658
@Cat.Aspirant123 said:
The average weight of 8 people decreases by 2 kgs, when two new people are added to thegroup. If the difference between the original weight and new weight is 36 kgs, find the new totalweight of the people.
260 ?
7659
The distance between Shyam's house and Suman's house is 16 kms. Shyam left his house at 7
a.m. and headed towards Suman's house at the rate of 5 km per hour. Suman left her house at 8 a.m.
and headed towards Shyam's house at the rate of 6 km per hour. At what time will they meet?
a) 11 a.m. b) 2 p.m. c) 10 a.m. d) 9 a.m. e) 12.00 noon
7660
@Cat.Aspirant123 said:
The average weight of 8 people decreases by 2 kgs, when two new people are added to thegroup. If the difference between the original weight and new weight is 36 kgs, find the new totalweight of the people.
260 ?