Question 27 - HABS Maths paper 2014

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AML
Posts: 347
Joined: Fri Sep 19, 2014 5:32 pm

Question 27 - HABS Maths paper 2014

Post by AML »

I am sure this is too easy, I make the answer 10 days but I feel its a trick question.
AML
Posts: 347
Joined: Fri Sep 19, 2014 5:32 pm

Re: Question 27 - HABS Maths paper 2014

Post by AML »

Here's the question


My friend George is really good at maths so I decide to ask him some tricky questions to see if I can catch him out. Needless to say he got it right.

Question

The area of mould growing on my bathroom wall doubles every day. After 13 days the area covered is 2880cm2. After how many days did the area first exceed 300cm2?
J50
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Joined: Wed Oct 10, 2012 10:35 am

Re: Question 27 - HABS Maths paper 2014

Post by J50 »

Yes easy just work backwards, halving.
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Question 27 - HABS Maths paper 2014

Post by Guest55 »

After 13 days the area covered is 2880cm2. After how many days did the area first exceed 300cm2?


So 12 days was .... 1440 cm^2.

11 days was 720 cm^2

10 days was 360 cm^2 so 9 days isn't over 300

Could you please post questions only once in future?
AML
Posts: 347
Joined: Fri Sep 19, 2014 5:32 pm

Re: Question 27 - HABS Maths paper 2014

Post by AML »

Apologies - last minute panic! Thanks for your reply. I thought it was supposed to be a trick question, looked TOO easy.
Guest55
Posts: 16254
Joined: Mon Feb 12, 2007 2:21 pm

Re: Question 27 - HABS Maths paper 2014

Post by Guest55 »

It's a 'inverse operation' question - ie working backwards. I bet a lot of children panicked and got it wrong.
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