MHB Understanding Algebra Division Formulas: SPI, EV, PV, and AC

AI Thread Summary
The discussion clarifies the relationship between the formulas SPI=EV/PV and CPI=EV/AC, showing that they are mathematically equivalent but serve different purposes. Rearranging these formulas allows for the calculation of one variable based on the others, depending on the available data. For instance, SPI can be used to find EV when PV is known, and vice versa. The confusion arises from the perception of having two solutions, but they are simply different interpretations of the same underlying relationships. Understanding these formulas aids in grasping the fundamentals of algebra in project management contexts.
falcios
Messages
3
Reaction score
0
If you rearrange this formula from SPI=EV/PV to EV=SPI*PV. Why is this formula like this: CPI=EV/AC is AC=EV/CPI
Aren't they basically the same.

Thanks for the help.
 
Mathematics news on Phys.org
We begin with:

$$CPI=\frac{EV}{AC}$$

Now, multiply both sides by $$\frac{AC}{CPI}$$:

$$CPI\cdot\frac{AC}{CPI}=\frac{EV}{AC}\cdot\frac{AC}{CPI}$$

$$AC\cdot\frac{CPI}{CPI}=\frac{EV}{CPI}\cdot\frac{AC}{AC}$$

$$AC\cdot1=\frac{EV}{CPI}\cdot1$$

$$AC=\frac{EV}{CPI}$$
 
I'm still lost aren't the two formulas basically the same why is there 2 different solutions?

Is there a simpler way to calculate for someone who is relearning the basics.

Thanks.
 
karush said:
also $SPI=EV/PV$ to $EV=SPI*PV$

it should be $SPI=EV/PV$ to $EV=SPI/PV$ you divide both sides by $PV$ to isolate $EV$

You want to multiply both sides by $PV$ to isolate $EV$.
 
Hello! I'm invading another thread. :o

Falcios, you are right. They are mathematically equivalent, as both Mark and Karush have shown you. However, what I think is really the issue here is: why bother with the equivalent versions?

The answer is that each version helps you calculate one quantity in terms of the others. When you write

$$\text{SPI} = \frac{\text{EV}}{\text{PV}}$$

you can find the value of SPI in terms of EV and PV. If, for some reason, you are given SPI and PV, you can find the value of EV in terms of these. Likewise, you can find the value of PV in terms of SPI and EV by doing the calculation

$$\text{PV} = \frac{\text{EV}}{\text{SPI}}.$$

In other words, there are not 2 "solutions", but two ways of interpreting results in light of what data you might have.

Hope this has helped. :D

Cheers!
 
Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Back
Top