In 1 kg mixture of sand and iron

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In 1 kg mixture of sand and iron

by BTGmoderatorDC » Thu Feb 08, 2018 5:29 pm
In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?

(a) 1kg
(b) 200gms
(c) 270gms
(d) 1.8kg
(e) 4.5kg

I'm confused how to set up the formulas here. Can any experts help?

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by Jeff@TargetTestPrep » Mon Feb 12, 2018 4:45 pm
lheiannie07 wrote:In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?

(a) 1kg
(b) 200gms
(c) 270gms
(d) 1.8kg
(e) 4.5kg
We see that 0.2 kg = iron and 0.8 kg = sand. If we let n = the amount of sand added, we can create the equation:

0.2/(1 + n) = 1/10

2 = 1 + n

1 = n

Answer: A

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