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Preliminary mathematics marathon (2 Viewers)

hscishard

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Omg'd.

A man in a rowing boat is 6km from the nearest point A on the shore. He wants to reach as soon as possible to point B that is a further 20km down the shore from A. If he can row at 8km/h and run 10km/h (pretty slow man), how far from A should he land?
 
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Omg'd.

A man in a rowing boat is 6km from the nearest point A on the shore. He wants to reach as soon as possible to point B that is a further 20km down the shore from A. If he can row at 8km/h and run 10km/h (pretty slow man), how far from A should he land?
8 km.
 

hscishard

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Finally got it. OMG.
Initially I just converted 1000 and 5000 to 1km and 5km. Thus the pythag, root x^2 + 1
After the first attempt I realised the speed was in m/s.

Went root (x^2+1000) :mad:
 

random-1005

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That helps heaps. My point B was like a 5km radius.

In 9b) i-iv are easy..
Not sure on v though. I'm sure this part is similar to the question above.


9 b part v is easy as well (but long), it just involves going back to part A and changing your cost formula to include the new the price given, and then you have to go through the whole process again differentiate , equal to zero etc. CHECK YOUR MAXIUM/MINIUM (even if you only have one answer) .
 
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New Question:

An A4 sheet of paper has equal squares cut from each corner to form a rectangular prism. What sized squares will give it the greatest volume?
 

random-1005

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if a and b are the roots of x^2 +px +q=0

find the equation whose roots are (a-b) and (b-a)
 

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