Steps to Solving Word Steps to Solving Word ProblemsProblems

1.1. Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

2.2. Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

3.3. Write an equation, and solve it.Write an equation, and solve it.4.4. State the answer to the problem.State the answer to the problem.5.5. Check your answer by Check your answer by

substituting in the problem.substituting in the problem.

How many millilitres of 50% acid solution must be mixed with 30% solution to produce 100 ml of 45% solution?

Things to Remember:Things to Remember:

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the State the answer to the problem.problem.

Check your answer by Check your answer by substituting in the substituting in the problem.problem.

Let x represent the amount of 50% solution.Let x represent the amount of 50% solution.

Let (100 - x) represent the amount of 30%.Let (100 - x) represent the amount of 30%.

Equation:Equation: 0.5x + 0.3(100 - x) = 0.45(100)

0.5x + 30 - 0.3x = 45

0.2x + 30 = 45

0.2x + 30 - 30 = 45 - 30

0.2x = 15

0.2x0.2

150.2

== x = 75 mlx = 75 ml

(Percent (Percent Question)Question)

How many millilitres of 50% acid solution must be mixed with 30% solution to produce 200 ml of 45% solution?

Things to Remember:Things to Remember:

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the State the answer to the problem.problem.

Check your answer by Check your answer by substituting in the substituting in the problem.problem.

Equation:Equation:

(Percent (Percent Question)Question)

How many millilitres of 50% acid solution must be mixed with 30% solution to produce 200 ml of 45% solution?

Things to Remember:Things to Remember:

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the State the answer to the problem.problem.

Check your answer by Check your answer by substituting in the substituting in the problem.problem.

Let x represent the amount of 50% solution.Let x represent the amount of 50% solution.

Let (200 - x) represent the amount of 30%.Let (200 - x) represent the amount of 30%.

Equation:Equation: 0.5x + 0.3(200 - x) = 0.45(200)

0.5x + 60 - 0.3x = 90

0.2x + 60 = 90

0.2x + 60 - 60 = 90 - 60

0.2x = 30

0.2x0.2

300.2

== x = 150 mlx = 150 ml

(Percent (Percent Question)Question)

A woman travels a certain distance by motor scooter at 50 km/h and returns at 60 km/h. Find the distance between the two places if the total travelling time was 11h.

Things to Remember:Things to Remember:

Use a chart to diagram informationUse a chart to diagram information

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the problem.State the answer to the problem.

Check your answer by substituting Check your answer by substituting in the problem.in the problem.11x

113300 11

==

x = 300 kmx = 300 km

(Distance, Time Question)(Distance, Time Question)

D (km)D (km) S (km/h)S (km/h) T (h)T (h)

XX 5050

xx 6060

Equation:Equation:

x50

x60

x50

x60

==++ 11

) x50(300 ) x

60(300 ==++ 300(11)

6x + 5x = 3300

11x = 3300

A woman travels a certain distance by motor scooter at 40 km/h and returns at 70 km/h. Find the distance between the two places if the total travelling time was 13h.

Things to Remember:Things to Remember:

Use a chart to diagram informationUse a chart to diagram information

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the problem.State the answer to the problem.

Check your answer by substituting Check your answer by substituting in the problem.in the problem.

(Distance, Time Question)(Distance, Time Question)

D (km)D (km) S (km/h)S (km/h) T (h)T (h)

Equation:Equation:

A woman travels a certain distance by motor scooter at 40 km/h and returns at 70 km/h. Find the distance between the two places if the total travelling time was 13h.

Things to Remember:Things to Remember:

Use a chart to diagram informationUse a chart to diagram information

Use a variable to represent the Use a variable to represent the unknown quantityunknown quantity

Express any other unknown Express any other unknown quantities in terms of this quantities in terms of this variable, if possible.variable, if possible.

Write an equation, and solve it.Write an equation, and solve it.

State the answer to the problem.State the answer to the problem.

Check your answer by substituting Check your answer by substituting in the problem.in the problem.11x

113640 11

==

x = 330.91 kmx = 330.91 km

(Distance, Time Question)(Distance, Time Question)

D (km)D (km) S (km/h)S (km/h) T (h)T (h)

XX 4040

xx 7070

Equation:Equation:

x40

x70

x40

x70

==++ 13

) x40(280 ) x

70(280 ==++ 280(13)

7x + 4x = 3640

11x = 3640

CLASS WORKCLASS WORK

►Check solutions to Lesson 3(2)Check solutions to Lesson 3(2)►Copy down examplesCopy down examples►Do Lesson 3(3) Assignment to hand in.Do Lesson 3(3) Assignment to hand in.