Question 22

View previous topic View next topic Go down

Question 22

Post by TECHNOTHLON on Thu Jul 21, 2016 11:38 am

Question 22 :
Tintin unlocks the chest, and plugs the key into the main door. A dial emerges on the door. Beginning with the dial set at zero, the dial must be turned counter-clockwise to the first combination number, (then clockwise back to zero), and clockwise to the second combination number, (then counter-clockwise back to zero), and counter-clockwise again to the third and final number, where upon the door shall immediately spring open. There are 40 numbers on the dial, including the zero. Without knowing the combination numbers, what is the maximum number of trials required to open the safe (one trial equals one attempt to dial a full three-number combination)?
(a) 64000 (b) 1600 (c) 63999 (d) 1599

TECHNOTHLON
Admin

Posts : 39
Join date : 2016-07-19

View user profile http://technothlon2016.boardonly.com

Back to top Go down

Re: Question 22

Post by ABC on Fri Jul 22, 2016 6:03 pm

Now in this question i hav huge doubt.. Is the combination "000" allowed as a password? If yes then the ans shud be (a), n if no thn (b).. I think we shud count 000 as it is a possible combination.. What abt others?

ABC
Guest


Back to top Go down

1600

Post by Arnav Bansal on Fri Jul 22, 2016 9:03 pm

I think the answer should be 1600..

Arnav Bansal
Guest


Back to top Go down

Re: Question 22

Post by Peeyush Sahu on Fri Jul 22, 2016 10:01 pm

The answer should be 64000.
This can be achieved by permutation and combination.
Three places each can be filled by 40 numbers .So, 40*40*40 =64000.☺☺☺

Peeyush Sahu
Guest


Back to top Go down

The Options don't seem to be correct.

Post by Chinmay Hebbar on Sat Jul 23, 2016 10:45 am

Using P&C,
we get 40*40*40 = 64,000.
But 000 won't be counted
=> 64,000-1 = 63,999.
But even 63,999 is WRONG.
Consider a case with 0.
Ex-
504
Here, when he turns the Knob from 5 back to 0, 0 is already counted.
Same goes for- 540, 054 or any no. with 0.
504, 054 & 540 are already counted while doing 541 or 542 or 54... .
This means any no. with 0 already gets counted.
So,
It will be 39*39*39 by P&C.
=> 59319

Chinmay Hebbar
Guest


Back to top Go down

Re: Question 22

Post by Peeyush Sahu on Sat Jul 23, 2016 3:32 pm

If all the digits are same like 111,222,333,444.... etc. Then ?

Peeyush Sahu
Guest


Back to top Go down

Answer is 1600

Post by Guest on Sat Jul 23, 2016 7:55 pm

it is so because.. total possible combinations are 40x40x40.. but in the question it is written that the lock will spring open in the 3rd rotation... so we can eliminate the trials of the 3rd rotation.. so the possible combinations are.. 40x40 =1600 Smile Very Happy

Guest
Guest


Back to top Go down

Re: Question 22

Post by Poirot on Sat Jul 23, 2016 9:04 pm

It might be 63999

Poirot
Guest


Back to top Go down

Re: Question 22

Post by Spiderman of India on Sun Jul 24, 2016 9:04 am

Ans is c)

Spiderman of India
Guest


Back to top Go down

Correction to my solution

Post by Chinmay Hebbar on Tue Jul 26, 2016 11:54 am

Here,
The solution (which is (d)) is obtained by -
Using Permutation&Combinations,
we get 40*40*1 (Since the last round, it opens immediately) - 1 (Case of 000) = 1599

However,
This solution is wrong Very Happy because-
If Consider a case with 0
For example,
504
Here, when he turns the Knob from 5 back to 0, 0 is already counted.
As stated in the passage "(then counter-clockwise back to zero)".
Same goes for- 540, 054 or any no. with 0.
504, 054 & 540 are already counted while doing 541 or 542 or 54... .
This means any no. with 0 already gets counted.
So,
It will be 39*39*1 by P&C.
=> 1521

Chinmay Hebbar
Guest


Back to top Go down

Re: Question 22

Post by All the best on Thu Jul 28, 2016 5:04 pm

Answer keys are available on Technothlon downloads page.Type your score here accordingly.

All the best
Guest


Back to top Go down

Re: Question 22

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum