How to find a ratio a1 - ACT Math

Assign a variable to science books since everything in the question can be written in terms of science books.

Write an expression for the phrase "twice as many comic books as science books."

To create an equation for the cost of the books, we can write the following:

Substitute in the known values and variables.

Jeff purchased 2 science books and 4 comic books.

Using the given information we can generate the following two proportions:

and

Next, cross-multiply each proportion to come up with the following two equations:

and

Each equation shares a term with the variable. We need to make this variable equal in both equations to continue. Multiply the first equation by a factor of 3 and the second by a factor of 2, so that the terms are equivalent. Let's start with the first equation.

Now, we will perform a similar operation on the second equation.

Now, we can set these equations equal to one another.

Drop the equivalent terms.

The proportion then becomes the following:

or

First, let's assign variables to the names of the individuals to represent their age in 2013.

In 2013, Molly was three times older than Steve; therefore, we can write the following expression:

We are also told that in 2016, Molly will be two times older than Steve; thus, we can write another expression:

.

We can then substitute in for in the second equation to arrive at the following:

Set up the proportions a/b = 9/2 and c/b = 5/3 and cross multiply.

2a = 9b and 3c = 5b.

Next, substitute the b’s in order to express a and c in terms of each other.

10a = 45b and 27c = 45b --> 10a = 27c

Lastly, reverse cross multiply to get a and c back into a proportion.

a/c = 27/10

In order to solve this problem, create an equation that summarizes the roof repair cost for each company. Begin by composing a formula for Company A, which charges 120 dollars upfront and 15 dollars per hour of labor.

Now, Company B charges 95 dollars upfront and 20 dollars per hour of labor. We can write the following equation:

The question asks us to find how many hours of labor that a repair must take in order for Company A to be cheaper than Company B. In other words, we need to compose an inequality in which the cost of Company A is less than the cost of Company B. We will substitute the variable for hours and solve.

Subtract from each side of the inequality.

Subtract 95 from both sides of the inequality.

Divide both sides of the inequality by 5.

If the repair will take more than 5 hours, Company A will be cheaper.

Since there are 5 defective radios, there are 45 nondefective radios; therefore, the ratio of non-defective to defective is 45 : 5, or 9 : 1.

Since the ratios are fixed, regardless of the actual values of , , or , we can let and

In order to convert to a form where we can relate to , we must set the coefficient of of each ratio equal such that the ratio can be transferred. This is done most easily by finding a common multiple of and (the ratio of to and , respectively) which is

Thus, we now have and .

Setting the values equal, we get , or a ratio of

For this problem, we need to find the number of employees who fall into the categories described, keeping in mind that multiple portions of the pie chart must be accommodated for. Then, we can fit them into a ratio:

For the "2 to 9 years" portion of the financial industry, include

(0.2 + 0.18)(12,000,000) = 4,560,000 workers.

For the "0 to 4 years" portion of the construction industry, include

(0.15 + 0.2)(8,000,000) = 2,800,000 workers.

Now divide and simplify to find the ratio:

4,560,000/2,800,000 = 8/5.

The ratio of green to blue is .

Without simplifying, the ratio of green to blue is (order does matter).

Since 3 and 9 are both divisible by 3, this ratio can be simplified to .

Let be the number of store employees, the number of store managers, and the number of corporate managers.

, so the number of store employees is .

, so the number of store managers is .

, so the number of corporate managers is .

Therefore, the number of employees who are either store managers or corporate managers is .

First, begin by calculating the total number of each item that there will be at the end of the process.

Cups:

Saucers:

The ratio of cups to saucers will thus be:

Assign a variable to science books since everything in the question can be written in terms of science books.

Write an expression for the phrase "twice as many comic books as science books."

To create an equation for the cost of the books, we can write the following:

Substitute in the known values and variables.

Jeff purchased 2 science books and 4 comic books.

Using the given information we can generate the following two proportions:

and

Next, cross-multiply each proportion to come up with the following two equations:

and

Each equation shares a term with the variable. We need to make this variable equal in both equations to continue. Multiply the first equation by a factor of 3 and the second by a factor of 2, so that the terms are equivalent. Let's start with the first equation.

Now, we will perform a similar operation on the second equation.

Now, we can set these equations equal to one another.

Drop the equivalent terms.

The proportion then becomes the following:

or

First, let's assign variables to the names of the individuals to represent their age in 2013.

In 2013, Molly was three times older than Steve; therefore, we can write the following expression:

We are also told that in 2016, Molly will be two times older than Steve; thus, we can write another expression:

.

We can then substitute in for in the second equation to arrive at the following:

Set up the proportions a/b = 9/2 and c/b = 5/3 and cross multiply.

2a = 9b and 3c = 5b.

Next, substitute the b’s in order to express a and c in terms of each other.

10a = 45b and 27c = 45b --> 10a = 27c

Lastly, reverse cross multiply to get a and c back into a proportion.

a/c = 27/10

In order to solve this problem, create an equation that summarizes the roof repair cost for each company. Begin by composing a formula for Company A, which charges 120 dollars upfront and 15 dollars per hour of labor.

Now, Company B charges 95 dollars upfront and 20 dollars per hour of labor. We can write the following equation:

The question asks us to find how many hours of labor that a repair must take in order for Company A to be cheaper than Company B. In other words, we need to compose an inequality in which the cost of Company A is less than the cost of Company B. We will substitute the variable for hours and solve.

Subtract from each side of the inequality.

Subtract 95 from both sides of the inequality.

Divide both sides of the inequality by 5.

If the repair will take more than 5 hours, Company A will be cheaper.

Since there are 5 defective radios, there are 45 nondefective radios; therefore, the ratio of non-defective to defective is 45 : 5, or 9 : 1.

Since the ratios are fixed, regardless of the actual values of , , or , we can let and

In order to convert to a form where we can relate to , we must set the coefficient of of each ratio equal such that the ratio can be transferred. This is done most easily by finding a common multiple of and (the ratio of to and , respectively) which is

Thus, we now have and .

Setting the values equal, we get , or a ratio of

For this problem, we need to find the number of employees who fall into the categories described, keeping in mind that multiple portions of the pie chart must be accommodated for. Then, we can fit them into a ratio:

For the "2 to 9 years" portion of the financial industry, include

(0.2 + 0.18)(12,000,000) = 4,560,000 workers.

For the "0 to 4 years" portion of the construction industry, include

(0.15 + 0.2)(8,000,000) = 2,800,000 workers.

Now divide and simplify to find the ratio:

4,560,000/2,800,000 = 8/5.

The ratio of green to blue is .

Without simplifying, the ratio of green to blue is (order does matter).

Since 3 and 9 are both divisible by 3, this ratio can be simplified to .