Problem Solving and Rational Numbers
Strategies for Problem Solving
1. READ THE PROBLEM AS MANY TIMES AS NECESSARY TO UNDERSTAND WHAT YOU NEED
2. Write down what is given including any formulas provided.
3. Determine all the necessary values used in the formula in order to solve the problem.
Problem 1: Temperature Conversion
Your family is planning on a vacation in Florida for the March break. You do a little research (on the
internet of course) and find that the average high temperature in Florida in March is 75 F.
The formula to convert Fahrenheit to Celsius is C ( F 32) . What is this temperature in Celsius?
Problem 2: Half-Life
Half-life is the time required for a substance to decrease in mass by half. The equation that models half-
life is t
c - is the original mass of the substance h - is the half-life
½ - is the decay factor M - is the mass of the substance after time t
t - is time
Given that a radioactive material has a half-life of one day. Thus, it decays according to the formula…
M 600 where M is the mass in grams and t is the time in days.
a) What is the initial mass of the material? _________________
b) How much of this material will remain after 7 days?
MPM 1D – Grade 9 Academic Math 1
Problem 3: Compound Interest
Compound interest occurs when the interest earned is added on to the original amount invested and
subsequent interest is calculated based on the total.
The formula for this is … A P 1 i where…
A – the total amount that the investment is worth
P – the original amount invested called the Principal
i – the interest per time period
n – the number of time periods
Alexandra worked at a clothing store in the summer and earned a total of $2500. She decides to invest
this money in a compound interest account that earns 4.5% interest per year. How much money is the
investment worth after 5 years?
Suppose the account earned interest every six months, what value would you need to change in the
above formula? __________________
Recalculate her investments worth.
CLASSWORK / HOMEWORK:
pg 55 #15
pg 63 #8 - 11
MPM 1D – Grade 9 Academic Math 2