A-CED Create equations that describe numbers or relationships.

1. Create equations and inequalities in one variable and use them to solve problems. Include equations arising from linear and quadratic functions, and simple rational and exponential functions.

Ratio ProblemThe ratio of girls to boys in Mrs. Franks’ Algebra class is 3:4 (excluding Mrs. Franks).

On Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students.

Since no other students were absent on Monday, the ratio of girls remaining in the class to boys remaining in the class was 4:5.

How many students are in Mrs. Franks’ classwhen everyone is present?

Understanding the ProblemThe ratio of girls to boys in Mrs. Franks’ Algebra class is 3:4 (excluding Mrs. Franks). On Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students. Since no other students were absent on Monday, the ratio of girls remaining in the class to boys remaining in the class was 4:5. How many students are in Mrs. Franks’ class when everyone is present?

Guess, Check and ReviseOn Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students.

If you there are only 3 girls and 4 boys in the class, there aren’t enough to send 4 girls and 6 boys on the fieldtrip.

Guess, Check and ReviseLets try adding in 3 more girls and 4 more boys to maintain the 3:4 ratio.

Now we have 6 girls and 8 boys in the class.

Guess, Check and ReviseOn Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students.

Guess, Check and ReviseOn Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students.

Now, there are 2 girls and 2 boys remaining in the class which is a 1:1 ratio.

We need to find a 4:5 ratio for the remaining students.

Repeat this approach until the remaining students are in the 4:5 ratio of girls to boys.

Write an Equation

If the ratio of girls to boys in the class is 3:4,

Then…The number of girls in the class =

The number of boys in the class =

The ratio of girls to boys in Mrs. Franks’ Algebra class is 3:4 (excluding Mrs. Franks).

Where x the common factor needed to maintain the ratio

On Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students.

If the # of girls in the class is 3x and The # of boys in the class is 4x,

Then…The number of girls remaining in class =

The number of boys remaining in class =

Write an Equation

Since no other students were absent on Monday, the ratio of girls remaining in the class to boys remaining in the class was 4:5

If the number of girls remaining in class = and the number of boys remaining in class =

Then…

Write an Equation

The ratio of girls to boys in Mrs. Franks’ Algebra class is 3:4 (excluding Mrs. Franks). On Monday, 4 girls and 6 boys got to go on a special field trip for honor roll students. Since no other students were absent on Monday, the ratio of girls remaining in the class to boys remaining in the class was 4:5. How many students are in Mrs. Franks’ class when everyone is present? Is 4 the solution

to this problem?

Solve the Equation

Answer the problem

If the common factor is

Then…The number of girls in the class =

The number of boys in the class =

How many students are in Mrs. Franks’ classwhen everyone is present?

Therefore, there are 28 students in Mrs. Frank’s class.

Check the answer