FACTOR LABEL / PROBLEM SOLVING

Chapter 4

Three step approach

1. Analyzea. What is known?b. What is unknown?c. Plan a solution strategy

2. Calculate3. Evaluate

a. Does my answer make sense?

Conversion Factors

You should know these conversion factors:

1 gram = 1000 mg (milligrams)1 gram = 100 cg (centigrams)1000 gram = 1 kg (kilogram)

Dimensional Analysis (Factor Label) Problem solving method

Example: How many miles is equal to 57.2 km?

Conversion factors:? miles = 57.2 km

0.621 mi = 1 km

57.2 km

1 km

0.621 mi = 35.5 mi

** Always start with the value equal to your unknown

** The next value should be your conversion factor

** The unit that you start with must be the unit on the bottom of the next conversion factor

Multi-step Problem

How many years old is a person who is 350,500,000 seconds old?

350,500,000 sec

60 sec

1 min = 11.11

years60 min

1 hr

24 hr

1 day

365 days

1 yr