Solve the problem.
-A contractor mixes concrete from bags of pre-mix for small jobs. How many bags with $6 \%$ cement should he mix with 5 bags of $18 \%$ cement to produce a mix containing $12 \%$ cement?
A) 10 bags
B) 5 bags
C) 15 bags
D) 7 bags

Question

Quizplus · Accepted Answer

The problem can be solved using the method of weighted averages. Let $x$ be the number of bags with $6\%$ cement needed. The total amount of cement from the $6\%$ bags is $0.06x$ and from the $18\%$ bags is $5 \times 0.18$. The total weight of the mix is $x + 5$ bags, and we want this mix to be $12\%$ cement. The equation is $0.06x + 5 \times 0.18 = 0.12(x + 5)$. Solving for $x$ gives $x = 5$.

Solve the Problem 6%6 \%6% Cement Should He Mix with 5 Bags Of

Solve the Problem $6 \%$ Cement Should He Mix with 5 Bags Of