Hello decoy808If , and and increase by small amounts and , then

, ignoring higher powers of , which we may do for small increases in

the fractional increase in the fractional increase in .

It is very easy show that this may be extended to a formula for which involves powers of any number of variables.

So, using the same method you may prove that if , then

With the percentage errors you have been given

and

So %

Grandad