Calculating Relative Speeds: Comparing Process X and Process Y in % Difference

[xeon123]

I have a really simple question that I can't figure it out.

I have a process X that took 905 seconds to finish. Process Y took 950 seconds to finish. I want to know a) how much in % process X is faster than Y, and b) how much in % process Y is slower than X?

I think that the answer is the following.

a) Taking X as reference, X is faster (X-Y)/Y times.
b) Taking Y as reference, Y is slower 1-(Y/X) times.

Am I correct?

 

[haruspex]

a) Taking X as reference, X is faster (X-Y)/Y times.
b) Taking Y as reference, Y is slower 1-(Y/X) times

That depends what you mean by X and Y there.
Since you want how much faster one is than the other, you need to compare rates.
What are the rates? You can express them as "processes per second"

 

[xeon123]

That depends what you mean by X and Y there.
Since you want how much faster one is than the other, you need to compare rates.
What are the rates? You can express them as "processes per second"

My question is not related to processes per second.
I have a process X which is faster than Y. I want to know how much X is faster than Y in %, and how much Y is slower than X in %. Eg., X is faster 10% than Y, and Y is slower something in % than X.

 

[haruspex]

My question is not related to processes per second

Alice walked a km in 15 minutes, Bob took 30 minutes. Alice was faster by 15 minutes, which is 50% less than 30, but was she only 50% faster? At 4km/h, wasn't she 100% faster than Bob's 2km/h?
"% faster" means you are comparing rates, not times.

 

[xeon123]

Alice walked a km in 15 minutes, Bob took 30 minutes. Alice was faster by 15 minutes, which is 50% less than 30, but was she only 50% faster? At 4km/h, wasn't she 100% faster than Bob's 2km/h?
"% faster" means you are comparing rates, not times.

I understand your example because you use numbers easy to calculate. I don't know how to answer my example. Can you tell me if my answers are correct?

 

[Mark44]

I have a process X that took 905 seconds to finish. Process Y took 950 seconds to finish. I want to know a) how much in % process X is faster than Y, and b) how much in % process Y is slower than X?

I think that the answer is the following.

a) Taking X as reference, X is faster (X-Y)/Y times.
b) Taking Y as reference, Y is slower 1-(Y/X) times.
Am I correct?

Using your numbers, for (a), you would get (905 - 950)/950, which is a negative number.
For (b), you would get 1 - (950/900), which is a number smaller than -1; i.e., more negative than -1.
So no, these are both incorrect.

I understand your example because you use numbers easy to calculate. I don't know how to answer my example. Can you tell me if my answers are correct?

See if you can duplicate @haruspex's thinking using your numbers.

 

[xeon123]

Using your numbers, for (a), you would get (905 - 950)/950, which is a negative number.
For (b), you would get 1 - (950/900), which is a number smaller than -1; i.e., more negative than -1.
So no, these are both incorrect.See if you can duplicate @haruspex's thinking using your numbers.

I am having some difficulty in duplicating @haruspex's example. I really need some help.

 

[haruspex]

I am having some difficulty in duplicating @haruspex's example. I really need some help.

Do as I suggested at the start - express the two rates as numbers of processes per second.