All ACT Math Resources
Example Questions
Example Question #72 : Algebra
Jen and Karen are travelling for the weekend. They both leave from Jen's house and meet at their destination 250 miles away. Jen drives 45mph the whole way. Karen drives 60mph but leaves a half hour after Jen. How long does it take for Karen to catch up with Jen?
She can't catch up.
For this type of problem, we use the formula:
When Karen catches up with Jen, their distances are equivalent. Thus,
We then make a variable for Jen's time, . Thus we know that Karen's time is (since we are working in hours).
Thus,
There's a logical shortcut you can use on "catching up" distance/rate problems. The difference between the faster (Karen at 60mph) and slower (Jen at 45mph) drivers is 15mph. Which means that every one hour, the faster driver, Karen, gains 15 miles on Jen. We know that Jen gets a 1/2 hour head start, which at 45mph means that she's 22.5 miles ahead when Karen gets started. So we can calculate the number of hours (H) of the 15mph of Karen's "catchup speed" (the difference between their speeds) it will take to make up the 22.5 mile gap:
15H = 22.5
So H = 1.5.
Example Question #24 : How To Find The Solution To An Equation
Bill and Bob are working to build toys. Bill can build toys in 6 hours. Bob can build toys in 3 hours. How long would it take Bob and Bill to build toys working together?
Bill builds toys an hour. Bob builds toys an hour. Together, their rate of building is . Together they can build toys in 2 hours. They would be able to build toys in 8 hours.
Example Question #25 : How To Find The Solution To An Equation
A hybrid car gets 40 miles per gallon. Gasoline costs $3.52 per gallon. What is the cost of the gasoline needed for the car to travel 120 miles?
The car will be using of gas during this trip. Thus, the total cost would be .
Example Question #73 : Algebra
Jon invested part of $16,000 at 3% and the rest at 5% for a total return of $680.
Quantity A: The amount Jon invested at 5% interest
Quantity B: The amount Jon invested at 3% interest
Quantity A is greater
The relationship cannot be determined from the information given
Quantity B is greater
The two quantities are equal
Quantity A is greater
First, let represent the invested amount at 3% and set up an equation like this:
Solve for , and you'll find that Jon invested $6,000 at 3% and $10,000 at 5%.
Example Question #74 : Algebra
Audrey, Penelope and Clementine are all sisters. Penelope is 8 years older than Clementine and 2 years younger than Audrey. If the sum of Penelope and Clementine's age is Audrey's age, how old is Clementine's age?
Let = Audrey's age, = Penelope's age, and = Clementine's age.
Since , then .
Furthermore, , and .
Through substitution, .
Example Question #75 : Algebra
If and , what is the value of ?
We could use the substitution or elimination method to solve the system of equations. Here we will use the elimination method.
To solve for , combine the equations in a way that makes the terms drop out. The first equation has and the second , so multiplying the first equation times 2 then adding the equations will eliminate the terms.
Multiplying the first equation times 2:
Adding this result to the second equation:
Isolate by dividing both sides by 7:
Example Question #32 : How To Find The Solution To An Equation
If and , then what is the value of ?
Since the expression we want just involves z and x, but not y, we start by solving for y .
Then we can plug that expression in for y in the first equation.
Multiply everything by 12 to get rid of fractions.
Example Question #33 : How To Find The Solution To An Equation
If , what is in terms of ?
Use inverse operations to isolate x. Working from the outermost part on the left side, we first divide both sides by 5.
To isolate the x term, subtract y from both sides.
Finally, isolating just x, divide both sides by 3.
Example Question #81 : Algebra
If , then, in terms of ,
Cannot be determined
You can solve this problem by plugging in random values or by simply solving for k. To solve for k, put the s values on one side and the k values on the other side of the equation. First, subtract 4s from both sides. This gives 4s – 6k = –2k. Next, add 6k to both sides. This leaves you with 4s = 4k, which simplifies to s=k. The answer is therefore s.
Example Question #82 : Algebra
The sum of two consecutive odd integers is 32. What is the value of the next consecutive odd integer?
Cannot be determined
Let be the smallest of the two consecutive odd integers. Thus,
and it follows that .
We have that 15 and 17 are the consecutive odd integers whose sum is 32, so the next odd integer is 19.