## CAT 2002 pblm

Expand Messages
• dear friends this is a straight CAT 2002 pblm. 7^6n-6^6n, where n is an integer 0 is divisible by 1. 13 2. 127 3. 559 4. all of these answer given is 1. (i.e)
Message 1 of 2 , Sep 2, 2003
dear friends
this is a straight CAT 2002 pblm.

7^6n-6^6n, where n is an integer >0 is divisible by

1. 13
2. 127
3. 559
4. all of these

answer given is 1. (i.e) 13.

my doubt is

1,x^n - a^n is exactly divisible by (x+a) when n is even
2,x^n - a^n is exactly divisible ny (x-a) irrespective of n

by this funda 1, we get two answers
1. 1st case (7^3)^2n-(6^3)^2n in this case it will be 7^3+6^3
which is 559.
2. 2nd case (7)^6n-(6)^6n in this case it will be 7+6 which is
13.
by funda 2, we get two answers
1. 1st case (7^2)^3n-(6^2)^3n in this case it is x-a so it is
13
2. 2nd case (7^3)^2n-(6^3)^2n in this case it is x-a so 7*7*7 -
6*6*6 which is 127

so the answer should be all of these.

but in the cat booklet they have taken into considetation only one
aspect. so how to go about it??

pblm 2

a watch ticks 90 times in 95 seconds and another watch ticks 315
times in 323 seconds. if both the watches are started together,
how many times will they tick together in the first hour?

ans is 101.
kly help me out

thanx and regards
subbu

___________________________________________________
Medicine meets Marketing; Dr. Swati Weds Jayaram.
Rediff Matchmaker strikes another interesting match !!
Visit http://rediff.com/matchmaker?2
• hi subbu well for the first problem, i have arrived at the same answer, i.e. all the options marked are correct. so perhaps there was a typing mistake in the
Message 2 of 2 , Sep 13, 2003
hi subbu
well for the first problem, i have arrived at the same answer, i.e. all the options marked are correct. so perhaps there was a typing mistake in the cat booklet answers!!!

for your second problem solution will be as follows:
The first watch ticks once every 95/90 seconds, and the second ticks once every 323/315 seconds
so they will tick together at the LCM of 95/90 and 315/323 i.e. 323/9 seconds

Therefore, every hour or every 3600 seconds they will tick together 3600/ (323/9) times or 100 times ( ignoring the remainder 100/323). But since they were started together, we add one more to the number of times they tick together hence answer is 101

Hope this would have helped
regards
subbu narayanaswamy <samarpan_subbu@...> wrote:
dear friends
this is a straight CAT 2002 pblm.

7^6n-6^6n, where n is an integer >0 is divisible by

1. 13
2. 127
3. 559
4. all of these

answer given is 1. (i.e) 13.

my doubt is

1,x^n - a^n is exactly divisible by (x+a) when n is even
2,x^n - a^n is exactly divisible ny (x-a) irrespective of n

by this funda 1, we get two answers
1. 1st case (7^3)^2n-(6^3)^2n  in this case it will be 7^3+6^3
which is 559.
2. 2nd case (7)^6n-(6)^6n in this case it will be 7+6 which is
13.
by funda 2, we get two answers
1. 1st case (7^2)^3n-(6^2)^3n  in this case it is x-a so it is
13
2. 2nd case (7^3)^2n-(6^3)^2n  in this case it is x-a so 7*7*7 -
6*6*6 which is 127

so the answer should be all of these.

but in the cat booklet they have taken into considetation only one
aspect. so how to go about it??

pblm 2

a watch ticks 90 times in 95 seconds and another watch ticks 315
times in 323 seconds.  if both the watches are started together,
how many times  will they tick together in the first hour?

ans is 101.
kly help me out

thanx and regards
subbu

___________________________________________________
Medicine meets Marketing; Dr. Swati Weds Jayaram.
Rediff Matchmaker strikes another interesting match !!
Visit http://rediff.com/matchmaker?2

Ascent Education
An IIM Alumni Venture
Class for CAT, XAT, GRE, GMAT
http://www.ascenteducation.com

Archives of past CAT questions can be viewed at http://www.ascenteducation.com/india-mba/iim/cat/questionbank/questionbank.shtml

To unsubscribe from this group, send an email to:
ascent4cat-unsubscribe@yahoogroups.com