## May 26, 2009

### Maths Challenge #6 – What Day is It?

Yesterday, Dad got confused about which day of the week it was. 'Whenever we go on holiday, I forget,’ he said.
‘Friday,’ said Darren.
‘Saturday,’ his twin sister Delia contradicted.
‘What day is tomorrow, then?’ asked Mum, trying to sort out the dispute without too much stress.
‘Monday,’ said Delia.
‘Tuesday,’ said Darren.
‘Oh, for Heaven’s sake! What day was it yesterday, then?’
‘Wednesday,’ said Darren.
‘Thursday,’ said Delia.
'Grrrrr!’ said Mum, ‘each of you has given one correct answer and two wrong ones.’

What day is it today?

### 16 comments by 5 or more people

1. #### Simon Whitehouse

It’s Friday. Darren got that right and Delia said that yesterday was Thursday.

Can I go home now?

26 May 2009, 11:01

2. #### Eleanor Lovell

You can’t go home just yet… you might need to re-read it! : )

26 May 2009, 11:02

3. #### Jake Dubber

It’s Saturday. The first sentence says “Yesterday, Dad got confused…” All of that happened yesterday. I think…

26 May 2009, 11:07

4. Saturday!
Even though someone already said it! You try to get us with your “yesterday etc…” I see your lies!

26 May 2009, 11:17

5. #### James Mears

Saturday – I got the trick, starts off in the past tense.

26 May 2009, 11:22

6. #### Simon Whitehouse

Aw, dammit, Janet. Got it wrong.

But if it’s Saturday I should be at home. Ciao

26 May 2009, 12:06

7. #### kdas

Yeah… saturday… that has less to do with logic then with attention to the words.

26 May 2009, 14:11

8. #### netci

All of that happened yesterday. I think…

26 May 2009, 20:10

9. #### Mathew Mannion

You’ve bested me again, Lovell.

26 May 2009, 21:59

10. Today is the day after yesterday.

26 May 2009, 22:47

11. Isn’t that tomorrow, today?

27 May 2009, 01:21

12. #### Eleanor Lovell

Just to clear up any confusion… the actual answer to yesterday’s challenge is SATURDAY.

Those who read it carefully will have noticed that the first sentence stated that the conversation took place yesterday. Darren’s answers imply that the day of the conversation is either Friday, Monday or Thursday. Delia’s imply that it is Saturday, Sunday or Friday. The only common day is Friday so that was when the conversation took place and TODAY is Saturday.

27 May 2009, 15:15

13. #### Nicola Hunt

But the question at the end was ‘What day is it today?’, so surely answering with the actual day you saw the #mathschallenge is the right answer?!!!

27 May 2009, 15:35

14. #### David

I think we should go this way:

yesterday’s discussion resulted in:

NAME / YESTERDAY / TODAY /TOMORROW
DARREN: wednesday friday tuesday
DELIA: thursday saturday monday

if one of them is correct, “today” has to either be friday or saturday.
as yesterday’s today is today, today might be saturday or sunday.

now we have to verify if mum’s statement remains true: they’re both telling 2 wrong answers and 1 correct answer.

possibility 1: today is saturday (hence “today” is friday)
T-TRUE
F-FALSE

NAME / YESTERDAY/ TODAY/ TOMORROW
DARREN: wednesday [F] friday [T] tuesday [F]
DELIA: thursday [T] saturday [F] monday [F]

the statement remains true.

possibility 2: today is sunday (hence “today” is saturday)

NAME: YESTERDAY/ TODAY/ TOMORROW
DARREN: wednesday [F] friday [F] tuesday [F]
DELIA: thursday [F] saturday [T] monday [F]

the statement doesnt remain true

therefore, today is saturday.

30 May 2009, 23:13

15. #### Tomás

I think my sister Mariana can awnser this.

30 May 2009, 23:16

16. #### David

“as yesterday’s today is today, today might be saturday or sunday.”
i mean
as yesterday’s tomorrow is today

30 May 2009, 23:18

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Warwick Challenges are mini academic challenges from University of Warwick professors, set via the micro-blogging service Twitter (and also via this blog).
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