Silver valued at $4.00 per gram must be mixed with how much gold valued at $24.00 per gram to
obtain 30 grams of an alloy worth $12.00 per gram?
(A) 12
(B) 12.5
(C) 13 (D) 13.4
(E)15
Answers
Answer
18 gms
Step-by-step explanation:
Equations:
Quantity Eq:::: s + g = 30 grams
Value Eq::::::: 4s +24g = 12*30 dollars
-------------------------------------------
Solving by Elimination:
Divide thru the Value Eq. by 4 to get:
s + 6g = 90
---
Subtract the Quantity Eq. from that to get:
5g =60
g = 12 grams (amt. of gold needed in the mixture)
----
Since s+g = 30, s = 18 grams (amt. of silver needed in the mixture)
Answer:
How much silver valued at $4 per gram must be mixed with gold valued at $24 per gram to obtain 30 grams of alloy worth $12.00 per gram?
Sat prep. Question.
Ans. 18grams
------------------------
Equations:
Quantity Eq:::: s + g = 30 grams
Value Eq::::::: 4s +24g = 12*30 dollars
-------------------------------------------
Solving by Elimination:
Divide thru the Value Eq. by 4 to get:
s + 6g = 90
---
Subtract the Quantity Eq. from that to get:
5g =60
g = 12 grams (amt. of gold needed in the mixture)
----
Since s+g = 30, s = 18 grams (amt. of silver needed in the mixture)