The Official CAT 2007 Quant Thread

[vineet.nitd]

Originally Posted by kondapalli

.


According to the rule of reflection, the angle of incidence (angle that the incident ray makes with the normal) is equal to the angle of reflection (angle that the reflected ray makes with the normal). A ray of light, originating perpendicularly at point P on the diameter AB of a semicircular mirror, is reflected at two points, D and E, on the mirror before passing through point B. What is the measure of angle POD?

P.S: don't the ans.

If <PDO=Q , then 5Q=270=>Q=54 =><POD= 90-54=36 degree

[kavish2000]

Originally Posted by kavish2000

my guess is the answer is POD=36 degree..its a stupid logic..but whast the answer?

I know its stupid but see
flip the semicircle and u will find a Half regular octagon...
so our angle is half the angle made by the side at the centre.that is 36
hehee

[vineet.nitd]

Okay guys solve these questions as a warm up to XAT ...

1. Rank of word Success considering you have to use only the alphabets in the given word .
2. If x+ 5y + 4z = 81 ( x,y,z >0 ) then what will be the maximum value of 5X + 3Y + 4Z ?
3. Find number of digits divisible by both 13 & 7 between 324 and 4032 with digits in ascending order of the number like abcd , where a < b < c< d ..
4. Find the general expression for sum of an AP HP mix - series.
5. Find no. of distinct rectangles of distinct dimensions framed between 9 X 9 lines with equal interspacing between them.

All the best

[esh.nil]

Originally Posted by vineet.nitd

Okay guys solve these questions as a warm up to XAT ...

1. Rank of word Success considering you have to use only the alphabets in the given word .
2. If x+ 5y + 4z = 81 ( x,y,z >0 ) then what will be the maximum value of 5X + 3Y + 4Z ?
3. Find number of digits divisible by both 13 & 7 between 324 and 4032 with digits in ascending order of the number like abcd , where a < b < c< d ..
4. Find the general expression for sum of an AP infinite series / AP HP mix - series.
5. Find no. of distinct rectangles of distinct dimensions framed between 9 X 9 lines with equal interspacing between them.

All the best

1) rank of success is 271
words with starting letter c - 120
with e - 60
with sc - 60
se - 30
su - success is the first word here, hence 271.

2)x=72, y =1 z =1 in x+5y+4z = 81
so the max value of the expression is 72*5+7 = 367
we have to maximise f(x,y,z) = 5x+3y+4z,
when I increase y or z by 1, the next increase in f() = -9*5+7 = -ve
hence 367 shld be the ans.
Hope I am right..

[krsh.vik]

Originally Posted by vineet.nitd

1. Find no. of distinct rectangles of distinct dimensions framed between 9 X 9 lines with equal interspacing between them.

All the best

12 13 14 15 .... 19
23 24 ..... 29
.
.
99

8*9/2
ANSWER : 36

fourth question kuch samaj me nahi aaya Please elaborate

[doomsayer]

Originally Posted by esh.nil

1) rank of success is 271
words with starting letter c - 120
with e - 60
with sc - 60
se - 30
su - success is the first word here, hence 271.

1) i got ans as 331.
eshnil i think u misss words start with ss ----60
so total 270+60+1=331

[kondapalli]

A number lock has a four-digit combination made by turning four wheels, each of which has the digits 0 through 9 in order. After 9 comes 0 again. Unfortunately, the lock is partially broken; each time you turn one of the four wheels, one of the adjacent wheels also turns. The correct combination to open the lock is 2000. From which of the following starting numbers is it possible to open the lock? More than one answer may be correct.
0000 1999 2001 3456 6543 7777 8161 8181

[abhrabumba]

Originally Posted by vineet.nitd

Okay guys solve these questions as a warm up to XAT ...

1. Rank of word Success considering you have to use only the alphabets in the given word .
2. If x+ 5y + 4z = 81 ( x,y,z >0 ) then what will be the maximum value of 5X + 3Y + 4Z ?
3. Find number of digits divisible by both 13 & 7 between 324 and 4032 with digits in ascending order of the number like abcd , where a < b < c< d ..
4. Find the general expression for sum of an AP HP mix - series.
5. Find no. of distinct rectangles of distinct dimensions framed between 9 X 9 lines with equal interspacing between them.

All the best

Hi...
Here are my takes:
1) Words with C - 6!/(3!*2!) = 60.
Words with E - 6!/(3!*2!) = 60.
Words with SC - 6!/(3!*2!) = 60.
Words with SE - 6!/(3!*2!) = 60.
Then comes our word - SUCCESS - 1
So rank = 241.

2) The variable x in the eqn x+5y+4z = 81 because this variable x is getting multiplied by 5 in the second eqn.
So putting y=z=1. we get x = 72.
Substituting this value in the second eqn. the max value of 5x+3y+4z = 367.

[blacof]

Originally Posted by abhrabumba

Hi...
Here are my takes:
1) Words with C - 6!/(3!*2!) = 60.
Words with E - 6!/(3!*2!) = 60.
Words with SC - 6!/(3!*2!) = 60.
Words with SE - 6!/(3!*2!) = 60.
Then comes our word - SUCCESS - 1
So rank = 241.

2) The variable x in the eqn x+5y+4z = 81 because this variable x is getting multiplied by 5 in the second eqn.
So putting y=z=1. we get x = 72.
Substituting this value in the second eqn. the max value of 5x+3y+4z = 367.

are x and y whole numbers ?

[abhrabumba]

Originally Posted by blacof

are x and y whole numbers ?

Well I assumed them to be whole numbers..... Donno if that was OK to do ....
Vineet bhai..iska answer kya hoga??