Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    5
    ReputationRep:
    Just been given this riddle by my uncle and I can't seem to solve it! :mad:

    I have X amount of money. If I had as many pounds as pence and many pence as pounds, I would have twice what I have. How much money do I have?

    And no, the answer is not 'I have X amount..' :P
    Offline

    1
    ReputationRep:
    (Original post by Clubba)
    Just been given this riddle by my uncle and I can't seem to solve it! :mad:

    I have X amount of money. If I had as many pounds as pence and many pence as pounds, I would have twice what I have. How much money do I have?

    And no, the answer is not 'I have X amount..' :P

    Clue: It is less than £100 apparently

    Let me try...

    Let X=A pounds + B pence
    convert into pence
    X=100A+B
    you have twice as many when you swap,
    2X=Bpounds +A pence
    convert into pence
    2X=100B +A
    equating the two

    200A+2B=100B+A
    199A=98B
    (199/98)A=B
    ...
    If X<100
    Since X= 100A+B
    100A+B<100
    100A+(199/98)A<100
    A<0.98
    Well, not sure if this is the way to do it.
    Offline

    2
    ReputationRep:
    Zero.
    Offline

    14
    ReputationRep:
    (Original post by whyeverynameisus)
    Let me try...

    Let X=A pounds + B pence
    convert into pence
    X=100A+B
    you have twice as many when you swap,
    2X=Bpounds +A pence
    convert into pence
    2X=100B +A
    equating the two

    200A+2B=100B+A
    199A=98B
    (199/98)A=B
    ...
    If X<100
    Since X= 100A+B
    100A+B<100
    100A+(199/98)A<100
    A<0.98
    Well, not sure if this is the way to do it.


    Please tell me you did not just try to solve a riddle with what you learn in maths class

    Offline

    12
    ReputationRep:
    I'm pretty sure this is easy peasy logic!

    Because we have unknown quantities the answer could, in heinseight, be anything.
    The closest we can get to an answer would be to examine the boundaries of pennies and pounds

    100p = £1
    1p = well, 1p

    The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
    So £2 and 2p is double £1 and 1p which would satisfy the riddle.

    Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

    Would love to know if I'm correct=p
    Offline

    20
    ReputationRep:
    (Original post by whyeverynameisus)
    Let me try...

    Let X=A pounds + B pence
    convert into pence
    X=100A+B
    you have twice as many when you swap,
    2X=Bpounds +A pence
    convert into pence
    2X=100B +A
    equating the two

    200A+2B=100B+A
    199A=98B
    (199/98)A=B
    ...
    If X<100
    Since X= 100A+B
    100A+B<100*100.....here is where you blundered
    100A+(199/98)A<100
    A<0.98
    Well, not sure if this is the way to do it.

    Have another go
    Offline

    14
    ReputationRep:
    (Original post by Acidy)
    I'm pretty sure this is easy peasy logic!

    Because we have unknown quantities the answer could, in heinseight, be anything.
    The closest we can get to an answer would be to examine the boundaries of pennies and pounds

    100p = £1
    1p = well, 1p

    The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
    So £2 and 2p is double £1 and 1p which would satisfy the riddle.

    Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

    Would love to know if I'm correct=p
    Offline

    1
    ReputationRep:
    (Original post by whyeverynameisus)
    Let me try...

    Let X=A pounds + B pence
    convert into pence
    X=100A+B
    you have twice as many when you swap,
    2X=Bpounds +A pence
    convert into pence
    2X=100B +A
    equating the two

    200A+2B=100B+A
    199A=98B
    (199/98)A=B
    ...
    If X<100
    Since X= 100A+B
    100A+B<100
    100A+(199/98)A<100
    A<0.98
    Well, not sure if this is the way to do it.
    I have to say... I can continue this and find two inequality, but is that what you want? the problem is that ,very likely, I can only find a range, instead of a exact answer.

    I pretty sure that Math is a way to solve question, otherwise, why Math exists?
    Offline

    1
    ReputationRep:
    (Original post by Acidy)
    I'm pretty sure this is easy peasy logic!

    Because we have unknown quantities the answer could, in heinseight, be anything.
    The closest we can get to an answer would be to examine the boundaries of pennies and pounds

    100p = £1
    1p = well, 1p

    The lowest amount we can have is 1p. So 1p and £1 is impossible, because they're both origins.
    So £2 and 2p is double £1 and 1p which would satisfy the riddle.

    Saying this there are alot of possible answers as you could more a less double anything up to 100. However this is evidently the origin and < £100.

    Would love to know if I'm correct=p
    That's the bit that I am talking about, are inequalities the answers?
    Offline

    2
    ReputationRep:
    This was on that Dara O'Briains maths show on dave.
    I remember working it out and then throwing the piece of paper in the bin :P
    Offline

    18
    ReputationRep:
    Is it meant to mean zero like someone suggested above? (zero is 2x0).

    I think that's the only answer. I thought about it and figured out that the pence has to be 50 or more (because it has to add more than a pound... if it was less than 50 and less than 2xpounds it wouldn't be enough, and if it was less than 50 and =/> 2xpounds then the pounds are not enough to make the pence be doubled. AWFUL explanation sorry but hopefully it makes sense to someone!)

    So then I started from 50 and went up, and 33.67 is the closest you can get.

    So in short yes he must mean zero!

    xxx
    Offline

    14
    ReputationRep:
    You have £99.99

    You start with £98 and 199p (£99.99)
    Switching pounds and pence you have £199.98 which is exactly double.
    Offline

    18
    ReputationRep:
    Very similar question here http://uktv.co.uk/dave/homepage/sid/9132 in question 5.

    Not sure yours is solvable, other than for 0.
    Offline

    0
    ReputationRep:
    Bear in mind both A and B have to be integers.

    (Original post by whyeverynameisus)
    I have to say... I can continue this and find two inequality, but is that what you want? the problem is that ,very likely, I can only find a range, instead of a exact answer.

    I pretty sure that Math is a way to solve question, otherwise, why Math exists?
    Offline

    0
    ReputationRep:
    The answer is 98 pounds and 199 pence. Confusing.... but correct.

    Sorry, posted two things separately which I meant to post together. Whoever did the simultaneous equations above did it correct but neglected to consider that A and B are integers. If you realise that then you're ok...
    Offline

    21
    ReputationRep:
    Ohh I thought I came to solve a riddle, not a ****ing maths question.
    Offline

    1
    ReputationRep:
    I got £99.99?

    Spoiler:
    Show
    Same method as whyeverynameisus:
    Let X=A pounds + B pence
    convert into pence
    X=100A+B (equation 1)
    you have twice as many when you swap,
    2X=Bpounds +A pence
    convert into pence
    2X=100B +A (equation 2)
    equating the two

    200A+2B=100B+A
    199A=98B
    (199/98)A=B
    Then did the same for A: 199A = 98B so A = (98/199)B

    used the fact that X < (100*100)p to say 100A + 199/98A < 100*100 A < (10,000/(100+199/98)) A < 98p
    Did the same for B and got it as < 199p which is just the two numbers we had relating them anyway xD

    Then just decided to substitute them into equations 1 and 2 using A = 98p and B = 199p
    and you get X = 100*98 + 199 = 9999p = £99.99
    so 2x should be £99.99 * 2 = £199.98
    sub into equation 2 to check: 2X = 100*199 + 98 = 19998p = £199.98p

    seems to work and the amount (£99.99) is juuuust under £100 but I've probably done something wrong :P
    • Thread Starter
    Offline

    5
    ReputationRep:
    Thanks for your replies guys Il take £99.99 as the answer :P
    Offline

    1
    ReputationRep:
    (Original post by Ansolon)
    The answer is 98 pounds and 199 pence. Confusing.... but correct.
    knew someone would've got it by the time I typed it out
 
 
 
Reply
Submit reply
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Updated: January 3, 2013
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What newspaper do you read/prefer?
    Useful resources
    AtCTs

    Ask the Community Team

    Got a question about the site content or our moderation? Ask here.

    Welcome Lounge

    Welcome Lounge

    We're a friendly bunch. Post here if you're new to TSR.

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.