The Official CAT 2007 Quant Thread

[Krack_CAT]

Hi,

Can neone tell me where i can find this book:

Abhijit Guha - Quantitative Apptitude for MBA.

I tried at fountain area and dadar, but no luck.

[mohit_353]

well guys ...i can't wait any more ...i am posting the first problem on number system.....
hope u guys will respond....

Ramu is given Rs 382 in one-rupee coins. He has been asked to
allocate them into a number of bags such that any amount required between Re
1 and Rs 382 can be given by just handling out a certain number of bags
without opening any of them. What is the minimum number of bags possible?
*****
***** a) 15
***** b) 13
***** c) 11
***** d) 17

i tried to come to the solution....

i tried with powers of 2 ( since we cannot open a bag )
the various bags he can have are, 1, 2, 4, 8, 16, 32, 64, 128 ( since 382 = 255 + 127 )
that is 8 bags

but it does not match any of the options...

tell me where i am wrong....

[karthikeyantcs]

Originally Posted by mohit_353

well guys ...i can't wait any more ...i am posting the first problem on number system.....
hope u guys will respond....

Ramu is given Rs 382 in one-rupee coins. He has been asked to
allocate them into a number of bags such that any amount required between Re
1 and Rs 382 can be given by just handling out a certain number of bags
without opening any of them. What is the minimum number of bags possible?
*****
***** a) 15
***** b) 13
***** c) 11
***** d) 17

i tried to come to the solution....

i tried with powers of 2 ( since we cannot open a bag )
the various bags he can have are, 1, 2, 4, 8, 16, 32, 64, 128 ( since 382 = 255 + 127 )
that is 8 bags

but it does not match any of the options...

tell me where i am wrong....

Hi buddy,In you solution tell me how are you going to give me say, Rs.350. You need to have 8 bags for Rs. 255. The remaining 127 should again be started with 1,2,4,8,16,32,64 bags ( 7 bags)we need to have 8 + 7 = 15 bags minimum. I hope it is clear.

[mohit_353]

Originally Posted by karthikeyantcs

Hi buddy,In you solution tell me how are you going to give me say, Rs.350. You need to have 8 bags for Rs. 255. The remaining 127 should again be started with 1,2,4,8,16,32,64 bags ( 7 bags)we need to have 8 + 7 = 15 bags minimum. I hope it is clear.

why can't we put 127 in one bag......i think in this way we can get all combinations...

& at last we need 9 bags...

wht to say......

[karthikeyantcs]

Originally Posted by mohit_353

why can't we put 127 in one bag......i think in this way we can get all combinations...

& at last we need 9 bags...

wht to say......

Still you did not understand the concept. Ok jus tell me how will you give me Rs.256?

[horrible]

Originally Posted by karthikeyantcs

Still you did not understand the concept. Ok jus tell me how will you give me Rs.256?

256 = 127 + 128 + 1


Mohit seems correct.

See, you can have any amount from 1 to 255 for sure.
Now, for any amount from 256 to 382, you will require bag carrying 127. If you just exclude 127 from the range (256 to 382), you get (129 to 255), which can be achieved by employing the other 8 bags from 1 to 128.

[karthikeyantcs]

Originally Posted by horrible

256 = 127 + 128 + 1


Mohit seems correct.

See, you can have any amount from 1 to 255 for sure.
Now, for any amount from 256 to 382, you will require bag carrying 127. If you just exclude 127 from the range (256 to 382), you get (129 to 255), which can be achieved by employing the other 8 bags from 1 to 128.

Yeah buddy you are right. Thanks a lot for the explanation.@Mohit,I am so sorry for my wrong explanation. You are correct. The answer is indeed 9 bags. Could you please check the solution from where you got this problem. Thanks a lot for the problem and I hope you will come with more problems like this.

[mohit_353]

Originally Posted by horrible

256 = 127 + 128 + 1


Mohit seems correct.

See, you can have any amount from 1 to 255 for sure.
Now, for any amount from 256 to 382, you will require bag carrying 127. If you just exclude 127 from the range (256 to 382), you get (129 to 255), which can be achieved by employing the other 8 bags from 1 to 128.

ya ...horrible is right...

[mohit_353]

Originally Posted by karthikeyantcs

Yeah buddy you are right. Thanks a lot for the explanation.@Mohit,I am so sorry for my wrong explanation. You are correct. The answer is indeed 9 bags. Could you please check the solution from where you got this problem. Thanks a lot for the problem and I hope you will come with more problems like this.

hey ...sory 4 wht..we r here to learn from each other..i must be thankful to u guys for taking interest ........

some more stuff......

1. 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 in the first hour?

A] 100
B] 101
C] 102
D] 99

2.How many 5 digit numbers can be made using 1, 2, 3, 4, 5 such that the digit in the unit

place is greater than the digit in the hundred's place ?

(1) 40 (2) 120 (3) 60 (4) 720


3. How many numbers can be formed by using 8,7,5,3,2 such that they are divisible by

125 ? Digits to be used exactly once.

(1) 20 (2) 4 (3) 2 (4) 1


4. A number when divided by 3 and 5 gives remainders 1 and 3. What will be the

remainder when the same number is divided by 15?

5. Two Trains A and B start from stations X and Y towards Y and X respectively. After

passing each other, they take 6 hours and 48 minutes and 3 hours and 20 minutes to

reach Y and X respectively. If train A is moving at 49 kms/hr, the speed of train B is..

Happy solving.........

[Krack_CAT]

Originally Posted by horrible

256 = 127 + 128 + 1


Mohit seems correct.

See, you can have any amount from 1 to 255 for sure.
Now, for any amount from 256 to 382, you will require bag carrying 127.
****I got this much
If you just exclude 127 from the range (256 to 382), you get (129 to 255), which can be achieved by employing the other 8 bags from 1 to 128.
**** I didn't understand this

i beg to differ....

with these 9 bags (1,2,4,8,16,32,64,128,127) you can get any value. i.e. from 1 to 382.

Even after all the ramayan and mahabharat, no one has posted the correct option.