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#1 2005-12-12 17:02:58

noorey711
Member
Registered: 2005-12-12
Posts: 2

I need help with integers

Robin Reed reported that the coldest day on record for his town was five times colder than
   
      yesterday's temprature, -4°C. What was the temprature of the coldest day in record in   

      Robin Reed's town?

do I have to divid -4÷5= [-4]÷[5]= 4÷5= -0.8

is this right?

View Image: disappearing_spots_illusion.gif

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#2 2005-12-12 17:57:42

justlookingforthemoment
Moderator
Registered: 2005-05-26
Posts: 2,161

Re: I need help with integers

You were on the right track, but instead of dividing, you should multiply.

-4 x 5 = -20°C

So, the coldest day was -20°C. Brr!

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#3 2005-12-12 18:02:39

noorey711
Member
Registered: 2005-12-12
Posts: 2

Re: I need help with integers

oh..
Thank you!!!

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#4 2005-12-12 18:04:00

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,535

Re: I need help with integers

Cool optical illusion !

(The website has more, but also LOTS OF ADS)


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#5 2005-12-12 18:05:45

justlookingforthemoment
Moderator
Registered: 2005-05-26
Posts: 2,161

Re: I need help with integers

What are you meant to do? smile

I've been staring at the middle and the flashing appears to be changing speeds, so I presume that's what's meant to happen.

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#6 2005-12-12 18:09:14

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,535

Re: I need help with integers

I get a phantom bright dot ... the eye over-compensates for the missing dot I think.


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#7 2005-12-13 00:13:07

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: I need help with integers

I get what MathsIsFun gets. Nothing at first, then a bright white dot where there should be nothing. It also has a hint of green for no apparent reason. Did anyone else get that or are my eyes weird?

The question raises an interesting point. How can you calculate how much is twice as cold?

Doing the same thing with °C, °F and K would return different answers. Also, what is twice as cold as 0°? What's the difference between twice as cold and twice as hot?

rotsnake2.gif


Why did the vector cross the road?
It wanted to be normal.

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#8 2005-12-13 08:29:47

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,535

Re: I need help with integers

That is one of the best optical illusions ever!

Quite right about "twice as cold", it really makes no sense for two reasons:

1. Temperature is just an arbitrary scale. To have it make sense, you would need to measure the amount of heat energy. Then you could say "this has twice as much heat".

2. Cold is just the absence of heat, so saying "twice as cold" is like saying "twice as poor".

Having said that, -20°C would still be the "commonly accepted" answer smile


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#9 2005-12-13 10:18:27

justlookingforthemoment
Moderator
Registered: 2005-05-26
Posts: 2,161

Re: I need help with integers

These optical illusions are great!

I see what you mean about temperature. It's kind of like saying 'I'm three times as short as you'. How can you be twice as short? It makes more sense when you say 'I'm a third as tall'. smile

I spent a long time playing with many more puzzling ones here:

http://www.michaelbach.de/ot/

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#10 2005-12-13 18:25:54

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,535

Re: I need help with integers

That is a great website ... what a collection.

I had to say to myself "later!" or I would get nothing done today.


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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