Solve the class boundary

The lower class boundary is found by subtracting 0.5 from the lower limit of each class.

• For $0-9$: Lower boundary $= 0 - 0.5 = -0.5$
• For $10-19$: Lower boundary $= 10 - 0.5 = 9.5$
• For $20-29$: Lower boundary $= 20 - 0.5 = 19.5$
• For $30-39$: Lower boundary $= 30 - 0.5 = 29.5$
• For $40-49$: Lower boundary $= 40 - 0.5 = 39.5$

The upper class boundary is found by adding 0.5 to the upper limit of each class.

• For $0-9$: Upper boundary $= 9 + 0.5 = 9.5$
• For $10-19$: Upper boundary $= 19 + 0.5 = 19.5$
• For $20-29$: Upper boundary $= 29 + 0.5 = 29.5$
• For $30-39$: Upper boundary $= 39 + 0.5 = 39.5$
• For $40-49$: Upper boundary $= 49 + 0.5 = 49.5$

The class boundaries are:

• $0-9$: $\boxed{-0.5 \text{ to } 9.5}$
• $10-19$: $\boxed{9.5 \text{ to } 19.5}$
• $20-29$: $\boxed{19.5 \text{ to } 29.5}$
• $30-39$: $\boxed{29.5 \text{ to } 39.5}$
• $40-49$: $\boxed{39.5 \text{ to } 49.5}$