Unit 6, Lesson 12
Changes on the Earth (Optional)
Accelerated 6
Practice
Problem 1
A research group is studying whether reading a book about running technique helps people run faster.
First, they time how long it takes 100 people to run 1 mile. Over the next week, 50 of the runners read the book. The other 50 runners do not read the book. One week later, they time how long it takes everyone to run 1 mile again.
- Of the 50 runners who did not read the book, 10 of them ran faster the second week.
- Of the 50 runners who did read the book, 18 of them ran faster the second week.
| total number of runners |
number who ran faster the second week |
|
|---|---|---|
| did not read the book |
50 | 10 |
| read the book | 50 | 18 |
- What percentage of the people who read the book ran faster the second week?
- When reporting their results, the research group says, “Reading this book led to an 80% increase in people improving their running speed.” What two quantities are they comparing to see an 80% increase?
- Do you think the research group’s sentence gives people an accurate representation of the results of their study? Why or why not?
to access Practice Problem Solutions.