Word Problems
Chapter 2, Sections 3 and 4
Solving Word Problems
1.
2.
3.
4.
5.
6.
Read the problem carefully.
Draw a picture (if you can) illustrating the problem.
Identify unknown quantities you're being asked to find.
Choose a variable to represent one quantity.
Write down, in words, what the variable (you chose in 4) represents.
Represent other quantities to be found in terms of the variable (you
chose in 4).
7. Write the word problem as an equation (hard step--takes practice).
8. Solve the equation for the unknown quantity.
9. Answer the question asked in the word problem.
10. Check your solution in the original word problem.
Some Common Formulas
Formula
Use
A = r2
Area of a circle.
r is the radius
C=2 r
Circumference of a circle.
r is the radius
A = LW
Area of a rectangle.
L is length, W is width
P = 2L + 2W
Perimeter of a rectangle.
L is length, W is width
1
A = BH
2
Area of a triangle.
B is base length, H is height
a2 + b2 = c2
Pythagoean theorem for a right triangle.
a, b lengths of legs
c length of hypotenuse
A = Prt
Simple interest.
A is interest earned,
P is the principal,
r is the interest rate (decimal),
t is time
Compound interest.
r nt
A = P(1 + )
A is interest earned,
n
P is principal,
r is interest rate (decimal),
n is number of times interest is paid per year,
t is time in years
A = Rt
Rates.
A is amount, R is rate, t is time
d = vt
Distance and speed.
d is distance, v is speed, t is time
5
C = (F - 32)
9
Temperature conversion.
F is degrees Fahrenheit
C is degrees Centigrade