Solve a Formula for a Specific Variable: example 9.57

Jamal rides his bike at a uniform rate of $12$ miles per hour for $3 \frac{1}{2}$ hours. How much distance has he traveled?

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Lindsay drove for $5 \frac{1}{2}$ hours at $60$ miles per hour. How much distance did she travel?

How did it go?

Step 1. Read the problem. You may want to create a mini-chart to summarize the information in the problem.	$d = ?$ $r = 12 mph$ $t = 3 \frac{1}{2} hours$
Step 2. Identify what you are looking for.	distance traveled
Step 3. Name. Choose a variable to represent it.	let d = distance
Step 4. Translate. Write the appropriate formula for the situation. Substitute in the given information.	$d = r t$ $d = 12 \cdot 3 \frac{1}{2}$
Step 5. Solve the equation.	$d = 42 miles$
Step 6. Check: Does 42 miles make sense?
Step 7. Answer the question with a complete sentence.	Jamal rode 42 miles.

Step 1. Read the problem. You may want to create a mini-chart to summarize the information in the problem.	$d = ?$ $r = 12 mph$ $t = 3 \frac{1}{2} hours$
Step 2. Identify what you are looking for.	distance traveled
Step 3. Name. Choose a variable to represent it.	let d = distance
Step 4. Translate. Write the appropriate formula for the situation. Substitute in the given information.	$d = r t$ $d = 12 \cdot 3 \frac{1}{2}$
Step 5. Solve the equation.	$d = 42 miles$
Step 6. Check: Does 42 miles make sense?
Step 7. Answer the question with a complete sentence.	Jamal rode 42 miles.