I’ll explain it with an example, say there is a cylinder whose diameter is known with a +/- 5 percent uncertainty, so this means the actual value could be at maximum 5% higher than the nominal value and the min 5% lower. What I’ve seen in a textbook is that in order to get the minimum possible value, they divided the nominal value (let’s call it d) by 1+ 5 percent : min=d/1.05
Why can’t they just multiply the nominal value by 0.95 just like how we multiply d by 1.05 to get the max value?
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Honestly, both are perfectly justified. d/1.05 = 0.9523d, which is very, very close to 0.95. If the difference between 0.95 and 0.9523 is important to you, then the manufacturer who reported 5% should have been far clearer. For instance, it’s highly unlikely it’s exactly 5.000%, the manufacturer probably just rounded to the nearest percent. That rounding error is larger than the difference you’re worried about.
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