Official Quant thread for CAT 2013

@vbhvgupta said:
explain kar do.
Find the sum upto 21 terms (-) sum upto 20 terms

N is the product of first 100 multiples of 5 starting from 5, then which is the rightmost nonzero digit of N ?

a 6
b 4
c 2
d NOT

@Tiws i think it will be 5
@vbhvgupta said:
expalin bhai...
i simply took an example and solved it.

1, (1/3), (1/9), (1/27)...

toh option B was giving the right ans.

otherwise, you can always go with the traditional method of solving though equations.
@Tiws said:
N is the product of first 100 multiples of 5 starting from 5, then which is the rightmost nonzero digit of N ?a 6 b 4 c 2 d NOT
5 ni hoga ??

Q. Number of 5 digit numbers with only 3 distinct digits. I do not have the options ppl

@coonal2006 said:
Q. Number of 5 digit numbers with only 3 distinct digits. I do not have the options ppl
p&c;
@coonal2006 said:
Q. Number of 5 digit numbers with only 3 distinct digits. I do not have the options ppl
PnC kamzor hai ...

agr 3 distinct me 0 include krte hain to 2*3*3*3*3 hona chaiye .. nhi include krte 0 to 3*3*3*3*3 ..


answer aur method dono postkrte tym tag kr dena :)
@coonal2006 i think it should be 9*9*8/3, not very confident
@Tiws said:
if f(x)= x^4 - 9x^3 + 26x^2 - 24x + 5 then one root of f(x) lies btwna)-1 &0b)0&2c)2&3d)4&5@raopradeepf(0) = 5 ; F(1) = -1 ;hence thr is a root between x=0 and x=1 thus option B is correct
there is the doubt sign change happens between 0&2 and
4&5
@Tiws said:
find remainder when S is devided by 13.S =[ 5+ 5^2 +......+ 5^ 55]a.0b.1c.7d.12
5^2mod13 =-1
5^3mod13=-5
5^4mod13=1
5^5mod13=5
a pair of 4 will cancel each other
so remaining ones are
5+ (-1) + (-5)
so remainder -1 or 12
OA d
@Tiws said:
N is the product of first 100 multiples of 5 starting from 5, then which is the rightmost nonzero digit of N ?a 6 b 4 c 2 d NOT
i am getting 5 what is the answer?
@coonal2006
22680
How many three-digit numbers are composed of three
distinct digits such that one digit is the average of the
other two?
(A) 96 (B) 104 (C) 112 (D) 120 (E) 256
@Tiws said:
N is the product of first 100 multiples of 5 starting from 5, then which is the rightmost nonzero digit of N ?a 6 b 4 c 2 d NOT
5?
@ishu1991 said:
How many three-digit numbers are composed of threedistinct digits such that one digit is the average of theother two?(A) 96 (B) 104 (C) 112 (D) 120 (E) 256
112 ways??
@ishu1991 said:
@coonal200622680

approach ??
@Tiws said:
N is the product of first 100 multiples of 5 starting from 5, then which is the rightmost nonzero digit of N ?a 6 b 4 c 2 d NOT
5*10*15...TILL 100 multiples.
5^100 (1*2*3......... *20)
= 5^104 * 2^18 * 3^8 * 7*2 * 11 * 13 * 17 * 19

this product would have 18 zeros.
so just find the unit digit of 5 ^ 86 * 3^8 * 7*2 * 11 * 13 * 17 * 19
= 5 * 1 * 9 * 1 * 3 * 7 * 9

Unit digit = 5
@ishu1991 said:
How many three-digit numbers are composed of threedistinct digits such that one digit is the average of theother two?(A) 96 (B) 104 (C) 112 (D) 120 (E) 256
From 0 to 9, select 2 odd digits or 2 even digits. That will give all possible AP's between 0 to 9.
So 2*5C2=20

For odd it will be 5C2*3!=60
For even, 0 will occur in 4 cases out of 10, so combinations will be 6*3!+4*(3!-2!)=52

ANS=112
@hiteshpratap
number shud be of form aaabc or aabbc
10c1*9*8*5!/3!*9/10 + 10c2*8*5!/2!2!*9/10