2. Example 1: Determine Reasonable Answers
Main Idea
Example 1: Determine Reasonable Answers
Lesson Menu

3. Solve problems by determining reasonable answers.
Main Idea/Vocabulary

4. Determine Reasonable Answers
GAMES Philip saw an advertisement for video games. One game costs $17.99 plus 5% tax. The other game costs $29.99 plus 5% tax. Philip has $60 saved to buy games. Can he afford both games? Explain.
Understand You know the cost of the two games, the tax rate, and how much money Philip has.
Plan Use mental math to determine a reasonable answer.
Example 1

5. Determine Reasonable Answers
Solve
Think $17.99 is close to $20 and $29.99 is close to $30. So, the two video games cost about $20 + $30 or $50.
The tax is half of 10% of $50. Since 10% of $50 is $5, half of 10% of $50 is $2.50. So, the total cost will be less than $50 + $2.50 or $52.50.
Answer: Since $52.50 is less than $60, Philip will have enough money.
Example 1

6. Determine Reasonable Answers
Check
$ ($20) = or $21
$ ($30) = or $31.50
The total cost is about $21 + $31.50 or $52.50, so the answer is reasonable. 
Example 1

7. MONEY Lorelei is buying new soccer shoes that cost $72
MONEY Lorelei is buying new soccer shoes that cost $72. She found them on sale for 80% of the original price. Would the sale price be about $30, $60, or $70?
A. $30
B. $60
C. $70
Example 1 CYP