Feed store - weighted averages

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Feed store - weighted averages

by bhumika.k.shah » Sat Feb 20, 2010 2:58 am
A feed store sells two varieties of birdseed: Brand A, which is 40% millet and 60% sun flower, and Brand B, which is 65% millet and 35% safflower (sunflower!). If a customer purchases a mix of the two types of birdseed that is 50% millet, what percent of the mix is Brand A?

Can someone explain the shortcut method.

P.s.: couldnt find this question and hence posted it.
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by harsh.champ » Sat Feb 20, 2010 3:43 am
bhumika.k.shah wrote:A feed store sells two varieties of birdseed: Brand A, which is 40% millet and 60% sun flower, and Brand B, which is 65% millet and 35% safflower (sunflower!). If a customer purchases a mix of the two types of birdseed that is 50% millet, what percent of the mix is Brand A?

Can someone explain the shortcut method.

P.s.: couldnt find this question and hence posted it.
Let brand A be x%
Then brand B is (100-x)%
So,we have 0.4*x + 0.65(100-x) = 50
Hence we can find x.
X comes out to be 60%(percent of Brand A in the mix)

If someone has a more shorter approach, plz let me know.
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by cheeseburst » Sat Feb 20, 2010 3:54 am
bhumika.k.shah wrote:A feed store sells two varieties of birdseed: Brand A, which is 40% millet and 60% sun flower, and Brand B, which is 65% millet and 35% safflower (sunflower!). If a customer purchases a mix of the two types of birdseed that is 50% millet, what percent of the mix is Brand A?


Sol:

.4A + .65B = .5(A + B)

.4A + .65B = .5A + .5B

A/B = 15/10

Now, 15 is what % of A+B i.e. 10+15=25 ?

15/25 = .6 = 60% Answer.

This is the simplest and the easiest way to solve this question.
Hope this helps.

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by shashank.ism » Sat Feb 20, 2010 8:55 am
bhumika.k.shah wrote:A feed store sells two varieties of birdseed: Brand A, which is 40% millet and 60% sun flower, and Brand B, which is 65% millet and 35% safflower (sunflower!). If a customer purchases a mix of the two types of birdseed that is 50% millet, what percent of the mix is Brand A?

Can someone explain the shortcut method.

P.s.: couldnt find this question and hence posted it.
Let X be the % of A added . so 40x+65(100-X) =50 x100 --> 25x=1500 --> x= 60% Ans.
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