Complete the Arithmetic Sequence: 20, 30, 40...

To complete the sequence $20, 30, 40, \ldots$, we need to determine the pattern.

• Identify the pattern: Find the difference between successive terms.
• Calculate the difference: $30 - 20 = 10$ and $40 - 30 = 10$. The common difference is 10.
• Continue the sequence using this pattern: Add 10 to the last given number to find the next number.
• Extend the sequence:
• The term after 40 is $40 + 10 = 50$.
• The next term is $50 + 10 = 60$.
• The next term is $60 + 10 = 70$.

Thus, the complete sequence is $20, 30, 40, 50, 60, 70$.

Therefore, the solution to the problem is $20, 30, 40, 50, 60, 70$, corresponding to choice 4.