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# Uncertainty question watch

1. If I'm dividing a number (with no uncertainty) by a value with uncertainty, to get my final value, what rules do I follow to get the uncertainty in the final value?

Ive tried:
1. dividing the number by the uncertainty
2. dividing the uncertainty in the value by the uncertainty, and then multiplying it with the final value

But I'm not sure which one is correct (if either of them are). Thanks!
2. So when u multiply or divide u add the percentage uncertainties. So imagine that the number with no uncertainty has 0% uncertainty.

If u know the uncertainty of the other number u can add these two uncertainties together to get the final percentage uncertainty.

Then its just a matter of converting from percentage to absolute which should be fairly straight forward.
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3. (Original post by IDontKnowReally)
If I'm dividing a number (with no uncertainty) by a value with uncertainty, to get my final value, what rules do I follow to get the uncertainty in the final value?

Ive tried:
1. dividing the number by the uncertainty
2. dividing the uncertainty in the value by the uncertainty, and then multiplying it with the final value

But I'm not sure which one is correct (if either of them are). Thanks!
See above👊🏾
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4. (Original post by Shaanv)
So when u multiply or divide u add the percentage uncertainties. So imagine that the number with no uncertainty has 0% uncertainty.

If u know the uncertainty of the other number u can add these two uncertainties together to get the final percentage uncertainty.

Then its just a matter of converting from percentage to absolute which should be fairly straight forward.
This is the alevel method right?
5. (Original post by IDontKnowReally)
This is the alevel method right?
Only one method for this question as far as im concerned, but yh it will work at a level.
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6. (Original post by Shaanv)
Only one method for this question as far as im concerned, but yh it will work at a level.
is there a method using just the absolute uncertainties?
7. (Original post by IDontKnowReally)
is there a method using just the absolute uncertainties?
Not in this instance, if ur adding or subtracting two numbers with uncertainty u use absolute uncertainties. If ur multiplying or dividing u use percentage uncertainties.
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