Solve the problem.
-A contractor mixes concrete from bags of pre-mix for small jobs. How many bags with $4 \%$ cement should he mix with 6 bags of $21 \%$ cement to produce a mix containing $10 \%$ cement?
A) 22 bags
B) 13 bags
C) 11 bags
D) 17 bags

Question

Quizplus · Accepted Answer

Let the number of bags with 4% cement be x. The total amount of cement in the 6 bags of 21% cement is $6 \times 21\% = 126\%$. The total amount of cement in the x bags of 4% cement is $x \times 4\%$. The total amount of cement in the mix is $126\% + x \times 4\%$. The total number of bags is $6 + x$. For the mix to contain 10% cement, the equation is $\frac{126 + 4x}{6 + x} = 10$. Solving for x gives $126 + 4x = 60 + 10x$, which simplifies to $6x = 66$, so $x = 11$.

Solve the Problem 4%4 \%4% Cement Should He Mix with 6 Bags Of

Solve the Problem $4 \%$ Cement Should He Mix with 6 Bags Of