Seem like it’s a problem with algebra:
Yes indeed. But he might be able to follow along in the video.
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The CG exam will not say which of the two equations to use. It has to be determined by what is given.
There is this one for speed / consumption problems
con1/con2= (S1^3) / (S2^3)
And this one for distance / consumption problems:
con1/con2 = (S1^2 *D1) / (S2^2 * D2)
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Can someone show me in detail the equation to work this one, while steaming at 18.9 kts, your vessel consumes 386 bbls a day. In order to reduce consumption to 251 bbls per day, what is the maximum speed the vessel can turn
Well whats the equation then
To solve the last problem you must know how to handle a third power root. If you haven’t had that elementary education you can forget about solving the problem. It is hardly maths more arithmetic. Best advice is to do a course on this stuff as to get a grip on material like this, it is not difficult at all. Groping around in the dark makes no sense.
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Same formula, different variables given.
Thanks again dutchie, it was the 3rd power root on that problem i was not applying.
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Thanks for doing what I asked, buddy. However, your cross multiplication is incorrect, you don’t multiple both sides by 386 as you show. But your error in showing work didn’t change the result so, good job!
Turns out you had the brains all along, Scarecrow.
You’re welcome.
The cross multiplication you used has made solving this example longer and more complicated then it needed to be.
This is correct:
251 / 386 = x^3 / 18.9^3.
But at this point just multiply both sides by 18.9^3
That gives:
18.9^3 * (251/386) = x^3
Then it’s just a matter of pushing the buttons on the calculator.
There is an alternative method to calculate this, namely with the help of logarithms.
251/386 = (x/18.9)^3
log 251/386 = 3(log x - log 18.9)
log (251/386)/3 = log x - log 18.9
log 18.9 + log (251/386)/3 = log x
1.276462 - 0.061175 = log x
1.214157 = log x
x = 16.37
Yes, you could get the highly coveted abacus endorsement on your credentials.
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I was a lazy student and having a good understanding of maths helped, it came to me almost naturally. To have a logical mind also helps. I hadn’t to learn and memorize too much stuff to get good maths grades.