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2012 Year 9 &10 Mathematics Marathon (3 Viewers)

ymcaec

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Re: 2012 Year 9 &10 Mathematics Marathon

heres one for ya, show that the some of the numbers 1+2+3...+99+100 = 5050

learnt that long time ago
(i hv seen this question in a yr 7 paper btw)
 

Demento1

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Re: 2012 Year 9 &10 Mathematics Marathon

For the benefit of more year 9 and 10 students here's a more moderate one for you guys:

An empty diving pool is in the shape of a rectangular prism, 6 metres long and 4 metres wide. Water is flowing into the pool at a rate of 800 litres per hour. What is the depth of the water after 5 hours?

NB: ymcaec, this would be too easy for you. Let some other people have a go.
 

kev-

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Re: 2012 Year 9 &10 Mathematics Marathon

An empty diving pool is in the shape of a rectangular prism, 6 metres long and 4 metres wide. Water is flowing into the pool at a rate of 800 litres per hour. What is the depth of the water after 5 hours?
Water after 5 hours
=800x5
=4000L

let a be height/depth
Volume of diving pool
=6x4xa
=24a m^3
=24000a L

equate: 24000a = 4000
a= 1/6 m
 

Triage

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Re: 2012 Year 9 &10 Mathematics Marathon

sinx-cosx=0 solve?
 

SpiralFlex

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Re: 2012 Year 9 &10 Mathematics Marathon

Who here would like to do a Spiral exam?
 

kazemagic

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Re: 2012 Year 9 &10 Mathematics Marathon

Here's another one:
Peter stands due south of a pole. Sam stands 10m due east of Peter. The angle of elevations of Peter and Sam to the top of the pole is 25(degrees) and 15(degrees) respectively. Find the height of the Pole.
 

kev-kun

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Re: 2012 Year 9 &10 Mathematics Marathon

Here's another one:
Peter stands due south of a pole. Sam stands 10m due east of Peter. The angle of elevations of Peter and Sam to the top of the pole is 25(degrees) and 15(degrees) respectively. Find the height of the Pole.
3.65 metres?
 

Demento1

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Re: 2012 Year 9 &10 Mathematics Marathon

o_O I got 3.27 for that one. How did you do it?
Sorry that I didn't see this Q earlier. After about 3/4 of a page of working, I had 3.27 metres. I treated the length of P to the pole as 7.02 (2 d.p.).
 

kat-

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Re: 2012 Year 9 &10 Mathematics Marathon

I feel like an idiot, can't get my head around this one. drew a 3D diagram and everything
 

Demento1

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Re: 2012 Year 9 &10 Mathematics Marathon

I feel like an idiot, can't get my head around this one. drew a 3D diagram and everything
Nah, don't worry too much about it. Never get thrown off by a question simply because it seems new to you. Make an effort to interpret it. If it doesn't hit you, take a break, have fun and relax and get back to the question once your mind is refreshed. Often, the human mind takes longer to comprehend things at times so it's perfectly normal not to get it the first time around.

When you do problem solving, think this: 'I have all this given information and thus I will record it but what do I need?'
 

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