Slyanite is a mineral that contains 28.0% gold by mass. How much sylvanite would you need to dig up to obtain 83.0g of gold

Question

lisa123 · Answer

@phi

vocaloid · Answer

set up a proportion

mass of gold/total mass = 28/100

that gives us

83.0/x = 28/100

solve for x

anonymous · Answer

Wouldn't it be 0.28 times 83?

vocaloid · Answer

not quite. if we wanted to know how much gold was in 83.0 grams of slyaniate, then yes, your approach would work, but the question wants to know how much sylvaniate has 83.0 g of gold

lisa123 · Answer

okay thank you @vocaloid I got the answer right!

phi · Answer

***Wouldn't it be 0.28 times 83? ***
no,  it would be 0.28 * unknown amount of mineral =  83 g pure gold
or
0.28 x= 83
solve for x

this will give the same answer as using proportions / ratios