To solve the problem, we need to find the total percentage increase in the investor's stock account after the increases in both companies' stock values.

Given:

• Company A's stock was worth $2220 last year and increased by 20%.
• Company B's stock was worth $7420 last year and increased by 5%.

Steps:

1. Find the increase in Company A's stock:

   • Percentage increase = 20% of $2220
   • Increase in Company A = $\frac{20}{100} \times 2220 = 444$
   • New value of Company A stock = $2220 + 444 = 2664$

2. Find the increase in Company B's stock:

   • Percentage increase = 5% of $7420
   • Increase in Company B = $\frac{5}{100} \times 7420 = 371$
   • New value of Company B stock = $7420 + 371 = 7791$

3. Find the total value of the stock account after the increases:

   • Total value now = $2664 + 7791 = 10455$

4. Find the total percentage increase in the account:

   • Original total value = $2220 + 7420 = 9640$
   • Total increase = $10455 - 9640 = 815$
   • Total percentage increase = $\frac{815}{9640} \times 100 = 8.5\%$

Final Answer:

The total percentage increase in the investor's stock account is 8.5%.

Would you like further clarification on any of these steps or more examples?

Here are some related questions to explore further:

1. How do you calculate the percentage change when the increase or decrease is a decimal value?
2. What would happen to the total percentage increase if the increase rates for both companies were higher?
3. How can we calculate the percentage decrease in a similar situation?
4. How would you approach solving a percentage change problem with multiple investments in different areas?
5. What’s the significance of rounding percentages in financial calculations?

Tip: Always check whether you need to round the final answer to the nearest tenth or hundredth for precision, especially in financial contexts!