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More help needed

Posted: Fri Jan 07, 2011 7:24 pm
by JGBallard
Please help with this one...

A school gate needs the correct combinationof four digits in the correct order

When 5648 is tried 2 digits are wrong
When 3628 is tried 2 digits are wrong
When 3147 is tried 2 digits are wrong
When 5629 is tried 2 digits are wrong
When 1258 is tried all the digits are wrong

What is the correct combination of digits?


Thank you

Re: More help needed

Posted: Fri Jan 07, 2011 8:23 pm
by stevew61
JGBallard wrote:Please help with this one...

A school gate needs the correct combinationof four digits in the correct order

When 5648 is tried 2 digits are wrong
When 3628 is tried 2 digits are wrong
When 3147 is tried 2 digits are wrong
When 5629 is tried 2 digits are wrong
When 1258 is tried all the digits are wrong

What is the correct combination of digits?


Thank you
1258 are all wrong so applying this,
*64* so 64 are correct
36** so 36 are correct
3*47 so 347...
*6*9.....69

Collecting in ORDER, 3,6,4, then 7 or 9? As two had to be wrong in 3*47, 7 is wrong leaves, 3649.

A version of VR codes.

Where did the question come from?

Re: More help needed

Posted: Fri Jan 07, 2011 8:39 pm
by JGBallard
Thank you so much! :)

Re: More help needed

Posted: Fri Jan 07, 2011 11:00 pm
by JGBallard
sorry, just looking at this again...I can see why the 8 is incorrect in the first line...but I'm lost after that..please help!

Thanks

Re: More help needed

Posted: Fri Jan 07, 2011 11:16 pm
by KS10
Take away 1 2 5 8 from all options as all 4 numbers are wrong.

So,

Option A: 5648 leaves you with 6 4 (two nos correct)
Option B: 3628 leaves you with 3 6 (two nos correct)
Option C: 3147 leaves you with 3 4 7 (two nos correct)
Option D: 5629 leaves you with 6 9 (two nos correct)

We know there's a 3 and a 4 in the code because the first two options are correct. That must mean there is no 7 in option C.

That leaves you with: 3 6 4 9 (option B shows you that 3 comes before 6 and option D shows you that 9 comes after 6).