Question

492 one digit is right but on the wrong place 561 one digit is right and is on the right place
209 all digits are wrong
451 two digits are right but both on the wrong place
843 one digit is right but on the wrong place

Answer 1

Case (1)

“4-9-2 one digit is right but on the wrong place.”

Case (2)

“5-6-1 one digit is right and is on the right place.”

Case (3)

“2-0-9 all digits are wrong.”

As all digits are wrong. So, remove or eliminate 2, 0 and 9 from all cases.

Now, from Case (1) and Case (3)

4 is the right digit. But it is places at wrong position. So, it's position my be second or third.

Case (4)

“4-5-1 two digits are right but both on the wrong place.”

Case (5)

“8-4-3 one digit is right but on the wrong place.”

From Case (1), Case (4) and Case (5)

We can say that 4 is at the third position.

Also, From Case (2) and Case (4)

1 is at same position.

Because according to Case (2) one digit is right and place at right position. But in Case (2) and (4) it is place at same position.

Also, from Case (2) and Case (4)

5 is at the first position.

0, 1, 2, 3, 6, 8, 9 [All are wrong and 5 and 4 are already filled. So, left one is 7]

Therefore, the correct code is 5-7-4

Answer 2

Given :-

→ 492 one digit is right but on the wrong place ---- Case(1)

→ 561 one digit is right and is on the right place..-- Case(2)

→ 209 all digits are wrong...----case(3)

→ 451 two digits are right but both on the wrong place..------case(4)

→ 843 one digit is right but on the wrong place..----- Case(5)

Answer :---

→ From case (1) & case (3) , we can Conclude That 4 is The right digit but at Wrong place .{since 2 & 9 are wrong in case (1) From Case (3). } So position of 4 is Either _ 4 _ or , _ _ 4.

→ Now, From case (5) one digit is right, ans that is our 4 and at wrong place, so we conclude that , position od 4 cant be in Middle.

So, Position of 4 is Fix Now . = _ _ 4.

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→ Now From case (4) , we have , in 451, two digits are right , we already have our Fixed number 4, so , we can conclude That , The other Number will be 5 or 1. And Position of Them are also incorrect.

→ Now, when we see in case(2) , we have one digit is right and is on the right place , and again we have both Number 5 or 1.

With These Two conclusion we can say That, Our 1 is not the Correct Number Because in case (4) position of 1 is at wrong place , and in case (2) , position of 1 is given same.

So, Our Right Number is 5 and its Position is Also Fixed . 5 _ _ .

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Now, with given conclusions we Also conclude That, 0, 1 , 2 , 3 , 6 , 8 & 9 are wrong keys..

So, we Only Left with 7. And Middle Position.

Hence, we can Conclude That :-

Final fixed key is :- 5 7 4.

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