ACT Math : Proportion / Ratio / Rate

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 : Proportion / Ratio / Rate

A rectangular container holds a liquid. The dimensions of the container are 5 cm by 5 cm by 4 cm. If the container is half full, how much liquid is in the container (1 cm= 1mL)?

Possible Answers:

50 mL

150 mL

20 mL

25 mL

100 mL

Correct answer:

50 mL

Explanation:

The total volume is 5 * 5 * 4 = 100 cm. Half of this is 50 cmwhich is 50 mL.

Example Question #1 : Proportion / Ratio / Rate

A dog eats \(\displaystyle 9\) treats in \(\displaystyle 4\) days. At this rate, how many treats does the dog eat in \(\displaystyle 4+x\) days?

Possible Answers:

\(\displaystyle \frac{9}{4}+4x\)

\(\displaystyle 9+\frac{x}{4}\)

\(\displaystyle \frac{9}{4}+\frac{x}{4}\)

\(\displaystyle \frac{9}{4}+\frac{9x}{4}\)

\(\displaystyle 9+\frac{9x}{4}\)

Correct answer:

\(\displaystyle 9+\frac{9x}{4}\)

Explanation:

This is a rate problem. We need to first find out how many treats a day the dog eats. Then to find the number of treats the dog eats in \(\displaystyle 4+x\) days, we multiply the number of days by the number of treats a day the dog eats.

From the given information, we know that the dog eats \(\displaystyle \frac {9}{4}\) treats a day.

Then we multiply that number by the number of days.

\(\displaystyle \frac{9}{4}(4+x)\)

 

Now simplify.

\(\displaystyle 9+\frac{9x}{4}\)

Example Question #1 : Proportion / Ratio / Rate

One serving of party drink is comprised of \(\displaystyle 3\:oz\) of syrup, \(\displaystyle 4\:oz\) of water, and \(\displaystyle 3\:oz\) of apple juice.  If a large bowl of the drink contains \(\displaystyle 237\:oz\) of apple juice, how much of the total drink is in the bowl?

Possible Answers:

\(\displaystyle 313\:oz\)

\(\displaystyle 553\:oz\)

\(\displaystyle 790\:oz\)

\(\displaystyle 79\:oz\)

\(\displaystyle 2730\:oz\)

Correct answer:

\(\displaystyle 790\:oz\)

Explanation:

The total drink is made up of \(\displaystyle 3+4+3=10\:oz\). Therefore, for a problem like this, you can set up a ratio:

\(\displaystyle \frac{x}{10}=\frac{237}{3}\)

First, simplify the right side of the equation:

\(\displaystyle \frac{x}{10}=79\)

Next, solve for \(\displaystyle x\):

\(\displaystyle x=790\).  Therefore, the total amount of drink is \(\displaystyle 790\:oz\).

Example Question #1 : Proportion / Ratio / Rate

There is a coffee drink made of \(\displaystyle 4\:oz\) of coffee, \(\displaystyle 3\:oz\) of milk, \(\displaystyle 2.5\:oz\) of cream, and \(\displaystyle 1\:oz\) of flavoring. If you have an unlimited amount of flavoring and milk but only \(\displaystyle 350\:oz\) of cream and \(\displaystyle 450\:oz\) of coffee, how many ounces of drink can you make? (Presume that you cannot make partial servings.)

Possible Answers:

\(\displaystyle 1384.15\:oz\)

\(\displaystyle 1176\:oz\)

\(\displaystyle 1181.25\:oz\)

\(\displaystyle 1050\:oz\)

\(\displaystyle 225.25\:oz\)

Correct answer:

\(\displaystyle 1176\:oz\)

Explanation:

To begin with, you need to compute what is going to be your limiting factor. For the cream, you can make:

\(\displaystyle \frac{350}{2.5}=140\) servings.

For the coffee, you can make:

\(\displaystyle \frac{450}{4}=112.5\) servings. 

Therefore, this second value is your total number of servings. (You must choose the minimum, for it will be what limits your beverage-making.)

So, you know that each drink is \(\displaystyle 4+3+2.5+1=10.5\:oz\).  If you can make \(\displaystyle 112\) servings (remember, no partial servings!), you can make a total of \(\displaystyle 112*10.5=1176\:oz\).

Example Question #4 : Proportion / Ratio / Rate

A drink is made up of \(\displaystyle 4\textup{ parts}\) orange juice to \(\displaystyle 7\textup{ parts}\) carbonated water.  If a bowl of this drink contains \(\displaystyle 161\textup{ cups}\)  of carbonated water, how many total cups of the drink are there in the bowl?

Possible Answers:

\(\displaystyle 253\)

\(\displaystyle 184\)

\(\displaystyle 281.75\)

\(\displaystyle 442.75\)

\(\displaystyle 92\)

Correct answer:

\(\displaystyle 253\)

Explanation:

To start this, you can set up a proportion as follows:

\(\displaystyle \frac{4}{7}=\frac{x}{161}\), where \(\displaystyle x\) is the number of cups of orange juice.

Now, solving for \(\displaystyle x\), you get:

\(\displaystyle x=92\)

Be careful, though! This means that the total solution is actually \(\displaystyle 92+161\) or \(\displaystyle 253\).

Example Question #1 : Proportion / Ratio / Rate

A solution has \(\displaystyle 30\textup{ ml}\) of solution X and \(\displaystyle 50\textup{ ml}\) of solution Y.  If you wanted a solution containing \(\displaystyle 240\textup{ ml}\) of solution Y, how much total solution would you need?

Possible Answers:

\(\displaystyle 504\textup{ml}\)

\(\displaystyle 384\textup{ml}\)

\(\displaystyle 424\textup{ml}\)

\(\displaystyle 144\textup{ml}\)

\(\displaystyle 158\textup{ml}\)

Correct answer:

\(\displaystyle 384\textup{ml}\)

Explanation:

To start, notice that the ratio of solution X to solution Y is:

\(\displaystyle \frac{3}{5}\)

Based on the quesiton, you know that you are looking for a certain amount of solution X based on a given amount of solution Y. Thus, for your data, you know:

\(\displaystyle \frac{3}{5}=\frac{x}{240}\)

Solving for X, you get:

\(\displaystyle x=144\)

This is the total amount of solution X that you will need to keep the ratios correct. Do not forget that you need to have a total solution amount, thus add this amount of solution X to solution Y's amount, thus giving you:

\(\displaystyle 144 + 240\) or \(\displaystyle 384\textup{ml}\)

Example Question #1 : How To Find A Ratio A1

The ratio of a to b is 9:2, and the ratio of c to b is 5:3. What is the ratio of a to c?

 

Possible Answers:

14:5

3:1

3:5

20:3

27:10

Correct answer:

27:10

Explanation:

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

 

 

 

Example Question #1 : How To Find A Ratio A1

There is a shipment of 50 radios; 5 of them are defective; what is the ratio of non-defective to defective?

Possible Answers:

1 : 5

5 : 50

50 : 5

9 : 1

1 : 9

Correct answer:

9 : 1

Explanation:

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.

Example Question #1 : How To Find A Ratio A1

A bag contains 3 green marbles, 5 red marbles, and 9 blue marbles.

What is the ratio of green marbles to blue marbles?

Possible Answers:

\dpi{100} \small 5:3\(\displaystyle \dpi{100} \small 5:3\)

\dpi{100} \small 3:5\(\displaystyle \dpi{100} \small 3:5\)

\dpi{100} \small 9:3\(\displaystyle \dpi{100} \small 9:3\)

\dpi{100} \small 1:3\(\displaystyle \dpi{100} \small 1:3\)

\dpi{100} \small 3:1\(\displaystyle \dpi{100} \small 3:1\)

Correct answer:

\dpi{100} \small 1:3\(\displaystyle \dpi{100} \small 1:3\)

Explanation:

The ratio of green to blue is \(\displaystyle 1:3\).

Without simplifying, the ratio of green to blue is \(\displaystyle 3:9\) (order does matter).

Since 3 and 9 are both divisible by 3, this ratio can be simplified to \(\displaystyle 1:3\).

Example Question #2 : Proportion / Ratio / Rate

A small company's workforce consists of store employees, store managers, and corporate managers in the ratio 10:3:1. How many employees are either corporate managers or store managers if the company has a total of \(\displaystyle 126\) employees?

Possible Answers:

\(\displaystyle 27\)

\(\displaystyle 18\)

\(\displaystyle 36\)

\(\displaystyle 9\)

\(\displaystyle 90\)

Correct answer:

\(\displaystyle 36\)

Explanation:

Let \(\displaystyle 10x\) be the number of store employees, \(\displaystyle 3x\) the number of store managers, and \(\displaystyle x\) the number of corporate managers.

\(\displaystyle 10x+3x+x=126\)

\(\displaystyle 14x=126\)

\(\displaystyle x=9\)

\(\displaystyle 10x=10\times9=90\), so the number of store employees is \(\displaystyle 90\).

\(\displaystyle 3x=3\times9=27\), so the number of store managers is \(\displaystyle 27\).

\(\displaystyle x=9\), so the number of corporate managers is \(\displaystyle 9\).

Therefore, the number of employees who are either store managers or corporate managers is \(\displaystyle 27+9=36\).

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