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In 1 kg mixture of sand and iron, 20% is iron. How much sand [#permalink]
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qlx 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
(f) 500gms


You can also use the scale method using the proportion of iron:

wSand/wMix = (20 - 10)/(10 - 0) = 1:1

So in 1 kg of mix, you must add 1 kg of sand.

Answer (A)

Originally posted by KarishmaB on 18 Aug 2014, 21:47.
Last edited by KarishmaB on 17 Oct 2022, 00:59, edited 1 time in total.
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Re: In 1 kg mixture of sand and iron, 20% is iron. How much sand [#permalink]
thanks for a cool question in the hot summers ( in india ) .. got to get a grip on these mixture problems... thanks to everyone for all the wonderful explainations
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Re: In 1 kg mixture of sand and iron, 20% is iron. How much sand [#permalink]
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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%?

Total Mixture = 1 Kg = 1000 Grams

Iron = 20% = 200 Grams

Sand = 80% = 800 Grams

We have make the 20% Iron to 10%

Which means we will make 200 Grams to 10% any additional sand which we are adding

200 = 10%(1000 + New Sand)

200 = 100 + 0.1 * New Sand

New Sand = 1000 Grams = 1 Kg

Hence, Answer is A
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Re: In 1 kg mixture of sand and iron, 20% is iron. How much sand [#permalink]
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Re: In 1 kg mixture of sand and iron, 20% is iron. How much sand [#permalink]
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