wontgiveup wrote:

hi all,

I have question below,i am not sure where i am goin wrng with my approach to solve it.

question

A dairy merchant adds 15% water to milk that costs $0.8 per liter and sells milk laced with water at $0.7.what % profit does he make?

My approach

Let there be 100 lits of milk

then, CP of100 lits of milk =0.8*85=68 (as 15% is water)

SP of 100 lits of milk =0.7*100=70

Therefore profit%=[(70-68)/68]*100=2.94%

which is not the right ans.I want know to wats wrong with my approach,I got few other questions wrong using same approach:(

A)1.66% B)6.25% C)1.25% D)0.625% E)1.667%

Read the first sentence "A dairy merchant adds 15% water to milk that costs $0.8 per liter... "

He adds 15% water. That means if milk is 100 lts, he adds 15 lts of water to it to make it 115 lts of mixture.

If milk were 85 lts, he will not add 15 lts of water but only 15% of 85 lts of water.

Whenever you have %, focus on % of what? Here you have 15%. This is 15% of the amount of pure milk. He adds 15% of the amount of pure milk. The base is amount of pure milk, not the amount of total mixture.

Now you can easily say the following:

Pure milk = 100 lts

Cost price = .8*100 = $80

Assuming water is free of cost,

Amount of mixture = 115 lts

Selling price = .7*115 = $80.5

Profit % = (80.5 - 80)/80 * 100 = .625% profit

_________________

Karishma

Veritas Prep GMAT Instructor

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