Algebra 1
Section 1.5
Using a Problem Solving Plan
Whenever you are given a problem:
1. Read the problem carefully and figure out what you know and what you need to find out.
2. Make a plan to solve the problem.
3. Carry out the plan – write an equation with variables and solve it.
4. Check that your solution is reasonable, then answer the question.
Some Useful Formulas:
9
Temperature: C  ( F  32)
5
Simple interest:
I=Prt
Distance traveled: D=rt
Profit: P = I – E
I = income & E = expenses
Examples:
1. You are responsible for buying the hamburger buns for an upcoming picnic. Each bag of buns
costs $1.30 and contains 8 buns. You need to buy a total of 64 buns. How much money will it
cost for the buns?
2.
Yesterday’s high and low temperatures were 51° F and 45° F. What are these temperatures in
degrees Celsius?
3. You are responsible for buying the lasagna for an upcoming birthday party. Each package of
lasagna costs $7.99 and serves 8 people. You need to buy enough packages so that each person
can have two servings. There will be 17 people at the party. How many packages do you need
to buy?
4. Last year the low temperature in your town was 32°F. The high temperature for the year was 3
times this temperature. What were last year’s high and low temperatures in degrees Celsius?
Round your answer to the nearest tenth of a degree.
5. The savings account in which you initially invested $250 has earned $30 in interest in 5 years.
What is the rate of interest of the account?