Need help slowing a Vinyl LP from 33 1/3 RPM to 25 RPM, my mind isn't figuring this out.

[shadowofward]

I'm trying to find the percent difference to a little problem i have. I need to slow down a LP Vinyl record from 33 1/3 RPM to 25 RPM. The difference is 8.33 however here the problem.

If 33.33 is technically 100% of the speed and 0 RPM = 0 % what is 8.33% of that 100% ?

11.11 RPM would be 33.33%
11.11 RPM would be 33.33%
11.11 RPM would be 33.33%

You see i need to slow a recording down in audacity from 33 1/3 RPM to 25 RPM so i need to know exactly what that percentage speed change is.

I hoped i explained my problem sufficiently. Can some kind soul help me out a bit please? Thanks!

 

[Otis]

If 33.33 is technically 100% of [33⅓]…

Hi shadowofward. Technically speaking, [imath]33.33[/imath] is 100% of [imath]33\frac{33}{100}[/imath], but we know what you meant.

One formula is:

\(\displaystyle \text{Percent Change } = \frac{\text{New } – \text{ Old}}{\text{Old}}\)

That gives the percent change in decimal form. As with all such percents, we multiply by 100% when we want to express them using a percent sign. Positive results indicate percent increase, and negative results indicate percent decrease.

\(\displaystyle \text{Percent Change } = \frac{25 \;–\; 33.33}{33.33} = \text{-}0.2499\)

-0.25 × 100% = -25%
[imath]\;[/imath]

 

[shadowofward]

Otis thank you! I'm so glad you understood my question. You math wizards amaze me, guess my brain just doesn't work well like that, i wish it did