Question

Sorry to bother but can someone help me understand this thank you so much.How many kilograms (kg) of pure salt must be added to 8 kg of a 30% solution to obtain a 35% solution? Round to the nearest tenth.

Answer 1

at the moment in solution 30% is pure salt

0.3*8 = 2.4kg of pure salt initially

lets say we add x kg of salt

now we have 2.4 + x kg of pure salt
in 8+x kg of total solution

we want the ratio pure:solution to be 35:100
we get the following equation because
\[\frac{pure}{total} = \frac{35}{100}\]
\[\frac{2.4+ x}{8+x} = \frac{35}{100}\]
\[2.4 + x = 0.35(8+x)\]
\[2.4 + x = 2.8 + 0.35x\]
\[x - 0.35x = 2.8 - 2.4\]
\[0.65x = 0.4\]
\[x = \frac{0.4}{0.65} = 0.615...\]

so 0.6 kg to the nearest tenth of a kilogram

Answer 2

I understand it much better now thank you so much I was getting confused thank you

Answer 3

:) happy to help