# problem involving triangle and profit

• July 19th 2011, 11:21 AM
landlord
problem involving triangle and profit

Due to previous tunneling experience, the firm estimates a cost of \$18,000 per meter for boring through this type of rock and constructing the tunnel according to required specifications. If management insists on a 30% profit, what will be their minimum bid to the nearest thousand.

The sides are 1200m, 1600m, 330.3m
Attached is the picture of the triangle that I worked out.

http://i56.tinypic.com/m93ltg.jpg

If someone can explain how to continue on from here that would be fantastic.

I had to use the cosine law to get the 330.3m, so I thought it would be relevant to post here.

-- Thanks
• July 19th 2011, 11:34 AM
e^(i*pi)
Re: problem involving triangle and profit
How did you get 330.3m? I used the cosine law to get 1175.2m for the "missing" side.

$c^2 = a^2+b^2 - 2ab\cos(C)$

$c = \sqrt{1600^2 + 1200^2 - 2 \cdot 1600 \cdot 1200 \cos(47^o)} \approx 1175.2\ m$
• July 19th 2011, 11:45 AM
landlord
Re: problem involving triangle and profit
Good catch, I didn't enter the numbers in proper order and got the wrong answer. When I put them in all at the same time it came out to be 1175.2

So, continuing on with the triangle and the 30% profit, any tips?
• July 19th 2011, 11:53 AM
e^(i*pi)
Re: problem involving triangle and profit
You have the cost per metre and the amount of metres.

To get a 30% profit on that you multiply the actual cost by 1.3
• July 19th 2011, 11:55 AM
landlord
Re: problem involving triangle and profit
Thanks for your help. Much appreciated.