+0  
 
0
65
3
avatar+16 

Mr. Butler is filling planter boxes with soil.  He has soil that is 30% sand, and he buys 9 pounds of a commercial potting soil that is 18% sand.  He mixes some of his soil with the 9 pounds of commercial potting soil.  The resulting soil mixture is 21% sand.  How many pounds of his soil did Mr. Butler use?

ForensicGirl  Feb 22, 2017

Best Answer 

 #3
avatar+10614 
+5

Soil sand content =   x * 30% = .3x

Commercial soil sand content = 9 x 18% = 1.62 pounds

 

resulting mixture is  (x+9) * 21%

 

added together must equal what is put in

.3x + 1.62 = .21 (x+9)

.3x + 1.62 = .21x + 1.89

.09x = .27

x= 3    pounds

ElectricPavlov  Feb 23, 2017
Sort: 

3+0 Answers

 #1
avatar
+5

Let the amount of Mr. Butler's 30% sand =S

0.30S + 0.18(9) =0.21(9+S)

0.30S + 1.62     =1.89 + 0.21S

0.30S - 0.21S =1.89 - 1.62

0.09S =0.27

S =0.27 / 0.09

S = 3 pounds - of 30% sand that Mr. Butler used.

Guest Feb 23, 2017
 #2
avatar+16 
+5

That's what we had.... I should really start learning to trust my gut.  Thank you so much for your expedient reply

ForensicGirl  Feb 23, 2017
 #3
avatar+10614 
+5
Best Answer

Soil sand content =   x * 30% = .3x

Commercial soil sand content = 9 x 18% = 1.62 pounds

 

resulting mixture is  (x+9) * 21%

 

added together must equal what is put in

.3x + 1.62 = .21 (x+9)

.3x + 1.62 = .21x + 1.89

.09x = .27

x= 3    pounds

ElectricPavlov  Feb 23, 2017

18 Online Users

avatar
avatar
avatar
avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details