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#1 2007-04-12 19:20:16

Insanic
Guest

order of magnitude

Determine the order of magnitude of the following calculations using approximation techniques and then obtain the significant figures for each calculation

a) 0.794 x 386 x 184;

b) 980 x 110 x 8 / 0.002 x 127

#2 2007-04-30 11:10:16

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,588

Re: order of magnitude

56000 or 56400, 2 or 3 sig figs, depending if you think you get less and less accurate as you go along.
Also consider using minimum values once, like: .793 x 385 x 183
and then compare to max values, like .795 x 387 x 185
Just a thought.


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#3 2007-04-30 11:38:28

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: order of magnitude

Maybe I'm reading the question wrong, but I don't think you actually need to estimate the answer.

The first part wants you to find the order of magnitude of the answer, and to do that you just find the orders of magnitude of each individual term and then combine them using power laws.

So for a), we have ~ 10^0 * 10^3 * 10^3 = 10^6.

Then to find the amount of significant figures, you would find the amount of significant figures in each individual term, then take the minimum of these. For a), each term is to 3 s.f., so the answer will also have 3 s.f.
For b) though, it varies a bit more.


Why did the vector cross the road?
It wanted to be normal.

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