A and B are both students of teacher Zhang's. Zhang's birthday is M(month)/N(date).Both of them know that Zhang's birthday is one of the following ten.
Mar 4th, Mar 5th, Mar 8th
Jun 4th, Jun 7th
Sep 1st, Sep 5th
Dec 1st, Dec 2nd, Dec 8th
One day Zhang told M to A, told N to B. Then Zhang asked if they had known his birthday.
A said: If I don't know, B can't know
B said: I didn't know at first, but now (after A's words) I know
A said: Oh I've know it too.
Question: What is Zhang's birthday?
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
His birthday cant be jun7 or Dec2 because then B would have known then he was told the date.
It cant be in Jun or Dec because then B could know then A don’t.
It cant be the 5th , because B wouldn’t know if it was Mar or Sep.
It cant be Mar, because A wouldn’t know if it was 4th or 8th.
So, its Sep 1th
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
His birthday cant be jun7 or Dec2 because then B would have known then he was told the date.
It cant be in Jun or Dec because then B could know then A don’t.
It cant be the 5th , because B wouldn’t know if it was Mar or Sep.
It cant be Mar, because A wouldn’t know if it was 4th or 8th.
So, its Sep 1th
Well done!!
How long did you work out it?
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
I don’t know how long it took me to solve it. Then I start to think of a problem like this, time flies for some reason. Then I had eliminated five possibilities I got stuck for quite a while. This was quite a tricky one, but also the first one I didn’t have to use a spreadsheet to collect my thoughts with.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
A and B are both students of teacher Zhang's. Zhang's birthday is M(month)/N(date).Both of them know that Zhang's birthday is one of the following ten.
Mar 4th, Mar 5th, Mar 8th
Jun 4th, Jun 7th
Sep 1st, Sep 5th
Dec 1st, Dec 2nd, Dec 8th
One day Zhang told M to A, told N to B. Then Zhang asked if they had known his birthday.
A said: If I don't know, B can't know
B said: I didn't know at first, but now (after A's words) I know
A said: Oh I've know it too.
Question: What is Zhang's birthday?
I've tried to figure this one out but to no avail. I've not been able to correlate the statements. Even after throwing out my scratch pad (filled with various variable doodles) and reading Ziran's answer... Thanks for posting the problem zc science. :)
�B said: I didn't know at first…�
We have 10 possible days, of these 10 days 8 share the number in the month with a day in an other month (ex. Mar 4th and Jun 4th). 2 of the days doesn’t, so then B was told the date it couldn’t have been 2 or 7 because he then would have known it was jun7 or Dec2.
8 possibilities left.
�A said: If I don't know, B can't know�
If A would have been told it was jun, it would have to be Jun 4th or Jun 7th. A wouldn’t have known if it was 4 or 7, but if B would have been told that it was 7th He would have known it had to be Jun 7th. So it cant be a month there B would know the birthday from just the date. Same reasoning for eliminating Dec.
5 possibilities left.
Now both A and B know that only these 5 possible birthdays remain: 4th Mar, 5th Mar,8th Mar,1th Sep, 5th Sep
�B said: I didn't know at first, but now (after A's words) I know�
B knows and know the date, so it have to be a date that only exist once among the remaining possibilities. The 5th exist twice 5th Mar and 5th Sep, so it cant be the 5th.
remaining: 4th Mar, 8th Mar,1th Sep
�A said: Oh I've know it too.�
A knows and know the month, so it have to be a month that only exist once among the remaining possibilities.
Mar exist twice, so Mar is eliminated.
We are now left with 1th Sep as the only possibility.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
There are four kids A B C and D playing soccer in the garden.
One of them broke the window.But when the owner of the house asked who broke the window, none of them admited that they had ever broken the window.
A said:" It was C who broke the window"
C said:" What A said was not true."
B said:" It wasn't me who broke the window."
D said:" It was A who broke the window."
We know only one of them told the truth.
Can you know who told the truth and who broke the window?
ps: sorry for my English :-)
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
If only one of them is telling the truth, then three of them is lying.
If B is lying he broke the window. A is then lying and therefore C is telling the truth. D is also lying.
If B is telling the truth, B didn’t brake the window and all others are lying.
One of A and C must be telling the truth, so B cant be the one telling the truth.
So, B broke the window and C is telling the truth.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
RE: 1+2+3+4+5+6+7+8*9.
)
The best answer of all! But I didn't think it of:)
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
A and B are both students of
)
A and B are both students of teacher Zhang's. Zhang's birthday is M(month)/N(date).Both of them know that Zhang's birthday is one of the following ten.
Mar 4th, Mar 5th, Mar 8th
Jun 4th, Jun 7th
Sep 1st, Sep 5th
Dec 1st, Dec 2nd, Dec 8th
One day Zhang told M to A, told N to B. Then Zhang asked if they had known his birthday.
A said: If I don't know, B can't know
B said: I didn't know at first, but now (after A's words) I know
A said: Oh I've know it too.
Question: What is Zhang's birthday?
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
Maybe I should have typed
)
Maybe I should have typed like this:"N(date)/M(month)" or 4th Mar.:-)
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
His birthday cant be jun7 or
)
His birthday cant be jun7 or Dec2 because then B would have known then he was told the date.
It cant be in Jun or Dec because then B could know then A don’t.
It cant be the 5th , because B wouldn’t know if it was Mar or Sep.
It cant be Mar, because A wouldn’t know if it was 4th or 8th.
So, its Sep 1th
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
RE: His birthday cant be
)
Well done!!
How long did you work out it?
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
I don’t know how long it
)
I don’t know how long it took me to solve it. Then I start to think of a problem like this, time flies for some reason. Then I had eliminated five possibilities I got stuck for quite a while. This was quite a tricky one, but also the first one I didn’t have to use a spreadsheet to collect my thoughts with.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
RE: A and B are both
)
I've tried to figure this one out but to no avail. I've not been able to correlate the statements. Even after throwing out my scratch pad (filled with various variable doodles) and reading Ziran's answer... Thanks for posting the problem zc science. :)
Lets se if I can make a more
)
Lets se if I can make a more detailed solution.
�B said: I didn't know at first…�
We have 10 possible days, of these 10 days 8 share the number in the month with a day in an other month (ex. Mar 4th and Jun 4th). 2 of the days doesn’t, so then B was told the date it couldn’t have been 2 or 7 because he then would have known it was jun7 or Dec2.
8 possibilities left.
�A said: If I don't know, B can't know�
If A would have been told it was jun, it would have to be Jun 4th or Jun 7th. A wouldn’t have known if it was 4 or 7, but if B would have been told that it was 7th He would have known it had to be Jun 7th. So it cant be a month there B would know the birthday from just the date. Same reasoning for eliminating Dec.
5 possibilities left.
Now both A and B know that only these 5 possible birthdays remain: 4th Mar, 5th Mar,8th Mar,1th Sep, 5th Sep
�B said: I didn't know at first, but now (after A's words) I know�
B knows and know the date, so it have to be a date that only exist once among the remaining possibilities. The 5th exist twice 5th Mar and 5th Sep, so it cant be the 5th.
remaining: 4th Mar, 8th Mar,1th Sep
�A said: Oh I've know it too.�
A knows and know the month, so it have to be a month that only exist once among the remaining possibilities.
Mar exist twice, so Mar is eliminated.
We are now left with 1th Sep as the only possibility.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.
There are four kids A B C and
)
There are four kids A B C and D playing soccer in the garden.
One of them broke the window.But when the owner of the house asked who broke the window, none of them admited that they had ever broken the window.
A said:" It was C who broke the window"
C said:" What A said was not true."
B said:" It wasn't me who broke the window."
D said:" It was A who broke the window."
We know only one of them told the truth.
Can you know who told the truth and who broke the window?
ps: sorry for my English :-)
Hello everyone!I'm Zhang Chi from China.I am 16 and I am a middle school student.And I love science. I want to be a scientist in the future!
If only one of them is
)
If only one of them is telling the truth, then three of them is lying.
If B is lying he broke the window. A is then lying and therefore C is telling the truth. D is also lying.
If B is telling the truth, B didn’t brake the window and all others are lying.
One of A and C must be telling the truth, so B cant be the one telling the truth.
So, B broke the window and C is telling the truth.
Then you're really interested in a subject, there is no way to avoid it. You have to read the Manual.