Official Quant thread for CAT 2013

MBA CAT 2024
15183
@Cat.Aspirant123 said:
x^2 + bx + c =0 is Sum of roots is greater den product of roots ?a) b is not greater den cb) b & c are positive integerseither/neither/1st/2nd/bothcan u tell me dis one sir ?
2nd alone
@raopradeep said:
q(x) is aquadratic eqn in x . it has a min. value of -28 when x=-3 . it has avalue of -10 when x=0 . find its value when x=4.a) 55b) 60c)65d)70
70 ?
15184
@raopradeep said:
q(x) is aquadratic eqn in x . it has a min. value of -28 when x=-3 . it has avalue of -10 when x=0 . find its value when x=4.
a) 55
b) 60
c)65
d)70
d) 70
ax^2 + bx + c is the quadratic equation ...
b = 6a ; c =- 10 ; b-3a = 6
15185
@Cat.Aspirant123 said:
x^2 + bx + c =0 is Sum of roots is greater den product of roots ?a) b is not greater den cb) b & c are positive integerseither/neither/1st/2nd/bothcan u tell me dis one sir ?
2nd alone?
15186
@bs0409 said:
A set of data consists of the following 5 numbers: 0,2,4,6, and 8. Which two numbers, if added to create a set of 7 numbers, will result in a new standard deviation that is close to the standard deviation for the original 5 numbers? (A) -1 and 9 (B) 4 and 4 (C) 3 and 5 (D) 2 and 6 (E) 0 and 8
option E. ?
15187
@ishu1991 said:
@Logrhythmhow product is equal to sun suppose if u take b=2 and c=2 then still sum of roots is -b and product of roots is c still -b is less than c
nah...i guessed ur confusing it with something
x^2-4x+4x=0 is our equation...
sum of roots = -b/a = -(-4) = 4
prod of roots = c/a = 4
=> sum = prod...

and more simply (x-2)^2 has 2 roots ie +2,+2
so prod=2*2=4
and sum=2+2=4

hope clear ho gaya aapko...
15188
The number of values of 'x' less than 30 for which 50! – x! ends in 6 zeroes ?

15189
@venomizer said:
The number of values of 'x' less than 30 for which 50! – x! ends in 6 zeroes ?
5 values??
25! to 29! - all have 6 zeroes...
(50!-25!) = 25!(50*49*48*...*26 - 1) = 10^6(50*49*48*...*26 - 1)
the value in the bracket does not end with a zero...hence only these 5 values...
15190
@venomizer
answer is 5
15191
@venomizer said:
The number of values of 'x' less than 30 for which 50! – x! ends in 6 zeroes ?
5 values?
25,26,27,28,29?
15192
@Harmeet89 25=5*5..
15193
@Harmeet89 said:
N is a natural number and P is the set {1,2,3,....2N}. Q denotes the average of all the odd elements of P and R denotes the average of all the even elements. Find R-Q.A) 1B) 0C) 2D) 1.5
1 ?
15194


@Harmeet89 said:
N is a natural number and P is the set {1,2,3,....2N}. Q denotes the average of all the odd elements of P and R denotes the average of all the even elements. Find R-Q.A) 1B) 0C) 2D) 1.5
let n=1
the set becomes (1,2)
Therefore,(2-1)=1
15195
@Harmeet89 said:
N is a natural number and P is the set {1,2,3,....2N}. Q denotes the average of all the odd elements of P and R denotes the average of all the even elements. Find R-Q.A) 1B) 0C) 2D) 1.5
1?
15196
@Harmeet89 said:
@Enigma001 What if P={1,2,3,4,5,6}?
2+4+6/3=4
1+3+5/3=3
4-3=1
15197
@Harmeet89 said:
N is a natural number and P is the set {1,2,3,....2N}. Q denotes the average of all the odd elements of P and R denotes the average of all the even elements. Find R-Q.A) 1B) 0C) 2D) 1.5
1??
take N=1
15198
@Harmeet89 said:
@Enigma001 What if P={1,2,3,4,5,6}?
This is the case when n=3;
Average of even nos =(2+4+6)/3 = 4
Average of odd nos = (1+3+5)/3 =3
Hence,(4-3)= 1
In order to make the calculations simpler ,I took the value of n as 1 .
15199
@Harmeet89 said:
N is a natural number and P is the set {1,2,3,....2N}. Q denotes the average of all the odd elements of P and R denotes the average of all the even elements. Find R-Q.A) 1B) 0C) 2D) 1.5
1??
odd number series is 1,3,5,....,2N-1
even number series is 2,4,6,....,2N
for odd no. series let us find the the number of terms in 2N-1. let us assume it to be the kth term. 2N-1=1+(k-1)*2
2N-1=1+2k-2
2N=2k
k=n

q= n/2[2*1+(n-1)*2]/n

similarly
2N= 2+(k-1)*2
k=n
R=n/2[2*2+(n-1)*2]/n

R-Q= n/2n[4+2(n-1)-2-2(n-1)]
= 1/2[4-2]
= 1/2*2=1
15200
In a room there are 7 persons . the chance that two of them were born on the same day of the week?
15201
@bs0409 said:
In a room there are 7 persons . the chance that two of them were born on the same day of the week?
2/7??

15202
@bs0409 said:
In a room there are 7 persons . the chance that two of them were born on the same day of the week?
7C2*7C1/7^7??

3/7^5??