# RATIONAL WORD PROBLEMS.

## Presentation on theme: "RATIONAL WORD PROBLEMS."— Presentation transcript:

RATIONAL WORD PROBLEMS

TO SOLVE RATIONAL WORD PROBLEMS

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up the unknowns in one variable.

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up the unknowns in one variable. 2. Set up an equation for the situation.

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up the unknowns in one variable. 2. Set up an equation for the situation. 3. Multiply by the common denominator to clear out fractions.

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up the unknowns in one variable. 2. Set up an equation for the situation. 3. Multiply by the common denominator to clear out fractions. 4. Solve the remaining equation for the variable.

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up the unknowns in one variable. 2. Set up an equation for the situation. 3. Multiply by the common denominator to clear out fractions. 4. Solve the remaining equation for the variable. 5. State final answers in real world terms.

Most tunnels are drilled using tunnel-boring machines that begin at both ends of the tunnel. Suppose a new underwater tunnel is being built and one tunnel-boring machine alone can finish the tunnel in 4 years. A different type of machine can tunnel to the other side in 3 years. If both machines start at opposite ends and work at the same time, when will the tunnel be finished?

Let x = number of years together

Let x = number of years together
Equation:

Let x = number of years together
Equation:

Solve equation: multiply by common denominator (4)(3)(x).

Solve equation: multiply by common denominator (4)(3)(x).

Solve equation: multiply by common denominator (4)(3)(x).

Solve equation: multiply by common denominator (4)(3)(x).

Solve equation: multiply by common denominator (4)(3)(x).

If both machines work toward each other it will take 1
If both machines work toward each other it will take 1.7 years to finish the tunnel.

If both machines work toward each other it will take 1
If both machines work toward each other it will take 1.7 years to finish the tunnel.

A car travels 300 km in the same time that a freight train travels 200 km. The speed of the car is 20 km/h more than the speed of the train. Find the speed of the car and the speed of the train.

Let x = speed of train Let x + 20 = speed of car
A car travels 300 km in the same time that a freight train travels 200 km. The speed of the car is 20 km/h more than the speed of the train. Find the speed of the car and the speed of the train. Let x = speed of train Let x + 20 = speed of car

Let x = speed of train Let x + 20 = speed of car
A car travels 300 km in the same time that a freight train travels 200 km. The speed of the car is 20 km/h more than the speed of the train. Find the speed of the car and the speed of the train. Let x = speed of train Let x + 20 = speed of car

Use the formula d = rt. Solve for “t”.

Use the formula d = rt. Solve for “t”.
t = d/r

Use the formula d = rt. Solve for “t”.
t = d/r

Use the formula d = rt. Solve for “t”.
t = d/r

Use the formula d = rt. Solve for “t”.
t = d/r

Solve: multiply by the common denominator (x + 20)(x).

Solve: multiply by the common denominator (x + 20)(x).

Solve: multiply by the common denominator (x + 20)(x).

Solve: multiply by the common denominator (x + 20)(x).

Solve: multiply by the common denominator (x + 20)(x).

Speed of train = x = 40 km/h

Speed of train = x = 40 km/h Speed of car = x + 20 = 60 km/h

Speed of train = x = 40 km/h Speed of car = x + 20 = 60 km/h

One electronic reader can read a deck of punched cards in half the time of another reader. Together they can read the deck in 8 minutes. How long would it take each reader alone to read the deck?

Let x = first reader time
One electronic reader can read a deck of punched cards in half the time of another reader. Together they can read the deck in 8 minutes. How long would it take each reader alone to read the deck? Let x = first reader time

Let x = first reader time Let 2x = second reader time
One electronic reader can read a deck of punched cards in half the time of another reader. Together they can read the deck in 8 minutes. How long would it take each reader alone to read the deck? Let x = first reader time Let 2x = second reader time

Let x = first reader time Let 2x = second reader time
One electronic reader can read a deck of punched cards in half the time of another reader. Together they can read the deck in 8 minutes. How long would it take each reader alone to read the deck? Let x = first reader time Let 2x = second reader time

Solve: multiply by common denominator (x)(8)

Solve: multiply by common denominator (x)(8)

Solve: multiply by common denominator (x)(8)

Solve: multiply by common denominator (x)(8)
First reader = x = 12 minutes Second reader = 2x = 24 minutes

One pipe can fill a tank in 6 hours while another can empty it in 2 hours. How long will it take to empty the full tank if both pipes are open at once?

Let x = time to empty full tank
One pipe can fill a tank in 6 hours while another can empty it in 2 hours. How long will it take to empty the full tank if both pipes are open at once? Let x = time to empty full tank

Let x = time to empty full tank Part empty - Part fill = Total empty
One pipe can fill a tank in 6 hours while another can empty it in 2 hours. How long will it take to empty the full tank if both pipes are open at once? Let x = time to empty full tank Part empty - Part fill = Total empty

Let x = time to empty full tank Part empty - Part fill = Total empty
One pipe can fill a tank in 6 hours while another can empty it in 2 hours. How long will it take to empty the full tank if both pipes are open at once? Let x = time to empty full tank Part empty - Part fill = Total empty

Solve: multiply by the common denominator (x)(6).

Solve: multiply by the common denominator (x)(6).

Solve: multiply by the common denominator (x)(6).

Solve: multiply by the common denominator (x)(6).

Solve: multiply by the common denominator (x)(6).
It will take 3 hours to empty the tank.

TO SOLVE RATIONAL WORD PROBLEMS
1. Set up variables. 2. Set up equation. 3. Multiply by the common denominator. 4. Solve for variables. 5. Define final answers.

PRACTICE TIME GO FOR IT!!!!