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PostPosted: Sun Aug 07, 2016 7:28 pm 
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Joined: Thu Oct 09, 2014 11:12 am
Posts: 85
Please can anyone help..
I can't seem to work this out for dd..
324 kg of coal to run a 100 watt bulb for 24 hours a day for a year
That's equal to the weight of 3 baby elephants

How many 100 watt bulbs could you run for 12 hours a day with 12 baby elephants weight of coal

Thanks


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PostPosted: Sun Aug 07, 2016 7:40 pm 
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Joined: Mon Feb 12, 2007 1:21 pm
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Quote:
[3 baby elephants] of coal to run a 100 watt bulb for 24 hours a day for a year

How many 100 watt bulbs could you run for 12 hours a day with 12 baby elephants weight of coal



OK take it one step at a time - 12 baby elephants would run bulbs for longer so ...

12 baby elephants of coal to run .... 100 watt bulbs for 24 hours a day for a year [assuming the time period is still a year?]

etc.


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PostPosted: Sun Aug 07, 2016 8:23 pm 
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Joined: Wed Mar 04, 2009 2:01 pm
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Location: Herts
You will do better if you post Maths questions in the Maths section.

There are lots of forum members willing to help.

Mods can you move this to the Maths section pls. DG


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PostPosted: Sun Aug 07, 2016 8:43 pm 
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Joined: Thu Oct 09, 2014 11:12 am
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Ok thank you

Please can it be moved mods


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PostPosted: Sun Aug 07, 2016 8:47 pm 
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Joined: Mon Mar 03, 2014 10:24 pm
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Location: Petts Wood, Bromley, Kent
8

3 into 12 = 4
Then double it as only running bulbs for half as much time.

Or am I over simplifying it and have it completely wrong?


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PostPosted: Sun Aug 07, 2016 8:55 pm 
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Yes answer is 8 but I could not work out how to get there

Thank you


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PostPosted: Sun Aug 07, 2016 9:16 pm 
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Joined: Tue Aug 02, 2016 5:05 pm
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First work out how many 100 watt bulbs you can run for 12 hours every day for a year with 3 baby elephants worth of coal (that's double the number of 100 watt bulbs you are able to run for 24 hours using the same 3 baby elephants - I.e. 2 x 1 = 2 bulbs).

Then work out how many 100 watt bulbs you can run for 12 hours every day for a year with four times as much coal (as 12 baby elephants is 4 times 3 baby elephants). I.e.

2 bulbs x 4 = 8.


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PostPosted: Sun Aug 07, 2016 9:21 pm 
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Joined: Thu Oct 09, 2014 11:12 am
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Thanks


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PostPosted: Tue Aug 23, 2016 11:59 am 
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Joined: Thu Sep 25, 2014 10:06 am
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just showed it to dd -
she says
3e -24 hrs for-1y
12e-24hrs for 12/3=4y
thus 12e-12 hrs =4x2=8y


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