Barbara is playing a game. She jumps forward 5 feet, and then steps backward 2 feet. How many jumps will it take her to reach the finish line, which is 20 feet from where she started?

Make a table to show Barbara's position.

Barbara will reach 20 feet on jump number _____?

It will take Barbara ______ jumps forward before she passes the finish line.

What did you find when you made the table?

Jump Number

Position After jump forward
Position after Step Back

I don't have any idea.

Good.

According to your table, on which jump will she reach 20 feet?

After 7 jumps foward and 6 backward.

Jump 1: 0 +5 -2 = + 3

Jump 2: 3 + 5 - 2 = +6

Thanks. Now I understand.

You're welcome.

Great! :-)

To find out how many jumps it will take Barbara to reach the finish line, we need to consider her position after each jump. We can create a table to track Barbara's position.

| Jump Number | Position |
|-------------|----------|
| 1 | 5 feet |
| 2 | 3 feet |
| 3 | 8 feet |
| 4 | 6 feet |
| 5 | 11 feet |
| 6 | 9 feet |
| 7 | 14 feet |
| 8 | 12 feet |
| 9 | 17 feet |
| 10 | 15 feet |
| 11 | 20 feet |

From the table, we can see that Barbara reaches the finish line on the 11th jump. Therefore, Barbara will reach 20 feet on jump number 11.

To calculate how many jumps forward Barbara needs to take to pass the finish line, we can subtract her current position from the finish line distance. In this case, 20 feet - 17 feet = 3 feet. So, it will take Barbara 3 more jumps forward before she passes the finish line.